Novel oxazine derivatives and their use in the treatment of disease

ABSTRACT

The invention relates to novel oxazine derivatives of formula (I), and pharmaceutically acceptable salts thereof, 
     
       
         
         
             
             
         
       
     
     in which all of the variables are as defined in the specification, pharmaceutical compositions thereof, combinations thereof, and their use as medicaments, particularly for the treatment of Alzheimer&#39;s Disease or diabetes via inhibition of BACE-1 or BACE-2.

FIELD OF THE INVENTION

The invention relates to novel oxazine derivatives and pharmaceuticallyacceptable salts thereof, pharmaceutical compositions thereof,pharmaceutical combinations thereof, and their use as medicaments,particularly for the treatment of neurodegeneration via inhibition ofBACE-1 or diabetes via inhibition of BACE-2.

BACKGROUND OF THE INVENTION

Alzheimer's Disease is a devastating neurodegenerative disorder. Itssporadic forms affect an elderly population (sharp increase in incidenceat >75 years of age), in addition, there are various familial forms withan onset of the disease in the fourth or fifth decade of life.Pathologically, it is characterized by the presence of extracellularsenile plaques, and intracellular neurofibrillar tangles in patient'sbrains. The core constituent of the senile plaques are small, 4 kDaamyloid peptides. They are generated by the proteolytic processing of alarge transmembrane protein, amyloid precursor protein (APP). Cleavageof APP by beta-secretase (BACE-1) releases the soluble APP-betafragment, while the 99-amino acid long C-terminus remains tethered tothe membrane. This C-terminal fragment is subsequently proteolyticallyprocessed by gamma-secretase (an membrane multi-enzyme complex) togenerate amyloid peptides of various length, predominantly 40 and 42amino acids long (Hardy J, Selkoe D J (2002) Science; 297(5580):353-356).

If, under pathologic conditions, the generation of these peptides occursat an increased rate, or if their removal from the brain is disturbed,increased brain amyloid peptide concentrations leads to the formation ofoligomers, fibrils and eventually plaques (Farris W, et al (2007) Am. J.Pathol.; 171 (1):241-251). It has been shown, that deposition of amyloidpeptides and plaques in the brain is the first measurable event in thepathogenesis of Alzheimers Disease, and that it is the trigger for lossof synapses, synaptic contacts, and neurons (Grimmer T, et al (2009)Neurobiology of Aging; 30 (12):1902-1909). Brain atrophy caused bymassive neuron loss is followed by impairments in cognition, memory,orientation and the ability to perform the tasks of daily living, i.e.clinically manifest dementia (Okello A, et al (2009) Neurology; 73(10):754-760).

BACE-1, also known as Asp2 or Memapsin 2, is a transmembrane asparticprotease highly expressed in neurons. It co-localizes with its substrateAPP in Golgi and endocytic compartments (Willem M, Lammich S, Haass C(2009) Semin. Cell Dev. Biol; 20 (2):175-182). Knock-out studies in micehave demonstrated the absence of amyloid peptide formation, while theanimals are healthy and fertile (Ohno M, et al (2007) Neurobiol. Dis.;26 (1):134-145). Genetic ablation of BACE-1 in APP-overexpressing micehas demonstrated absence of plaque formation, and the reverse ofcognitive deficits (Ohno M, et al (2004) Neuron; 41 (1):27-33). BACE-1levels are elevated in the brains of sporadic Alzheimer's Diseasepatients (Hampel H, Shen Y (2009) Scand. J. Clin. Lab. Invest.; 69(1):8-12).

Taken together, these findings suggest that the inhibition of BACE-1 maybe a favourable therapeutic strategy for the treatment of Alzheimer'sDisease.

Beta-site amyloid precursor protein cleaving enzyme 2 (BACE-2) is atransmembrane aspartic protease that is highly expressed in pancreatic βcells and other peripheral tissues (Brian D. Bennett, Safura Babu-Khan,Richard Loeloff, Jean-Claude Louis, Eileen Curran; Martin Citron, andRobert Vassar (2000) J J. Biol. Chem. 275(27) 20647-20651). BACE-2 isclosely related to BACE-1 or beta secretase. However, despite structuraland sequence similarities the substrate specificity of BACE-1 and BACE-2appear to be different. While Aβ or β-amyloid peptide is the mainsubstrate of BACE-1, BACE-2 does not generate either form of Aβ (Vassar,R., Bennett, B. D., Babu-Khan, S., Kahn, S., Mendiaz, E. A., Denis, P.,Teplow, D. B., Ross, S., Amarante, P., Loeloff, R., Luo, Y., Fisher, S.,Fuller, J., Edenson, S., Lile, J., Jarosinski, M. A., Biere, A. L.,Curran, E., Burgess, T., Louis, J.-C., Collins, F., Treanor, J., Rogers,G., and Citron, M. (1999) Science 286, 735-741).

Transmembrane protein 27 (TMEM27 or collectrin) plays an important rolein β-cell proliferation and insulin secretion (Pinar Akpinar, SatoruKuwajima, Jan Krützfeldt, and Markus Stoffel (2005) Tmem27: CellMetabolism. 2(6) 385-397) and has been identified as a substrate forBACE-2 (WO 2010/063718). Tmem27 exists as a dimer and the extracellulardomain is cleaved and shed from the plasma in a β cell-specific manner.Overexpression of full-length Tmem27, but not the truncated or solubleprotein, increases β cell proliferation, suggesting that the full lengthprotein is required for this biological function. Tcf1 (hepatocytenuclear factor-1α, HNF-1α) controls the transcription of TMEM27. Micewith targeted deletion of Tcf1 exhibit decreased β cell mass, andknockdown of Tmem27 using RNAi results in a reduction of cellproliferation. Transgenic mice with increased expression of Tmem27 inpancreatic β cells exhibit increased β cell mass compared to theirwild-type littermates. This data indicates that TMEM27 plays a role incontrol of β cell mass and that inhibition of BACE-2 which cleavesTMEM27 could be useful for treating loss of β cell mass and function,the underlying cause of diabetes.

Taken together, these findings suggest that the inhibition of BACE-2 maybe a favourable therapeutic strategy for the treatment and prevention ofmetabolic disorders related to decreased β cell mass and/or function,such as type 2 diabetes.

Oxazine derivatives having BACE-1 and/or BACE-2 activity are describedin the literature, for example WO 2011/069934 A1. However, there is anongoing requirement for further structurally diverse BACE inhibitorswhich may have improved properties in terms of their inhibitoryactivity, selectivity, solubility, metabolism, pharmacokinetics and/orsafety profile. It may also be advantageous to identify compounds whichshow selective inhibitory activity for BACE-1 over BACE-2 or BACE-2 overBACE-1.

SUMMARY OF THE INVENTION

The present invention therefore relates to novel oxazine derivativeshaving BACE inhibitory activity, to their preparation, to their medicaluse and to medicaments comprising them.

More particularly, in a first aspect the invention relates to a compoundof the formula (I), or a pharmaceutically acceptable salt thereof:

whereinR¹ and R² are independently hydrogen or halogen;R³ and R⁴ are independently hydrogen or C₁₋₃alkyl; or R³ and R⁴ takentogether are cyclopropyl; or R¹ and R⁴ are hydrogen and R² and R³ takentogether are —CH₂—O—CH₂—;R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl; andR⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising 1,2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl.

More particularly, in a second aspect the invention relates to acompound of the formula (I), or a pharmaceutically acceptable saltthereof:

whereinR¹ and R² are independently hydrogen or halogen;R³ and R⁴ are independently hydrogen or C₁₋₃alkyl; or R³ and R⁴ takentogether are cyclopropyl;R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl; andR⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising 1,2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl.

More particularly, in a third aspect the invention relates to a compoundof the formula (I), or a pharmaceutically acceptable salt thereof:

whereinR¹ and R² are independently hydrogen or halogen;R³ and R⁴ are independently hydrogen or C₁₋₃alkyl; or R³ and R⁴ takentogether are cyclopropyl;R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl; andR⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising 1,2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy and C₁₋₄alkoxy-C₁₋₄alkylthio.

DEFINITIONS

As used herein, the term “C₁₋₄alkyl” refers to a straight or branchedhydrocarbon chain radical consisting solely of carbon and hydrogenatoms, containing no unsaturation, having from one to four carbon atoms,and which is attached to the rest of the molecule by a single bond.Examples of C₁₋₄alkyl include methyl, (R)-methyl, ethyl, n-propyl,1-methylethyl (iso-propyl) n-butyl and 1,1-dimethylethyl (t-butyl). Theterm “C₁₋₃alkyl” refers to alkyl radicals as defined herein having fromone to three carbon atoms.

As used herein, the term “C₂₋₄alkenyl” refers to a straight or branchedhydrocarbon chain radical group consisting solely of carbon and hydrogenatoms, containing at least one double bond, having from two to fourcarbon atoms, and which is attached to the rest of the molecule by asingle bond. Examples of C₂₋₆alkenyl include, ethenyl, prop-1-enyl andbut-1-enyl.

As used herein, the term “C₂₋₄alkynyl” refers to a straight or branchedhydrocarbon chain radical group consisting solely of carbon and hydrogenatoms, containing at least one triple bond, having from two to fourcarbon atoms, and which is attached to the rest of the molecule by asingle bond. Examples of C₂₋₄alkynyl include ethynyl, prop-1-ynyl andbut-1-ynyl.

As used herein, the term “C₁₋₄alkoxy” refers to a radical of the formula—O—R_(a) where R_(a) is a C₁₋₄alkyl radical as defined above. Examplesof C₁₋₄alkoxy include methoxy, ethoxy, propoxy, isopropoxy, butoxy andisobutoxy. The term “C₁₋₃alkoxy” is to be construed accordingly.

As used herein, the term “C₁₋₄alkoxy-C₁₋₄alkyl” refers to a radical ofthe formula —R_(a)—O—R_(a) where each R_(a) is independently a C₁₋₄alkylradical as defined above. The oxygen atom may be bonded to any carbonatom in either alkyl radical. Examples of C₁₋₄alkoxy-C₁₋₄alkyl includemethoxy-methyl, methoxy-ethyl, ethoxy-ethyl, 1-ethoxy-propyl and2-methoxy-butyl. The term “C₁₋₃alkoxy-C₁₋₃alkyl” is to be construedaccordingly.

As used herein, the term “C₁₋₄alkoxy-C₁₋₄alkoxy” refers to a radical ofthe formula —O—R_(a)—O—R_(a) where each R_(a) is independently aC₁₋₄alkyl radical as defined above. The oxygen atoms may be bonded toany alkyl radical carbon atom. Examples of C₁₋₄alkoxy-C₁₋₄alkoxy includemethoxy-methoxy, methoxy-ethoxy, ethoxy-ethoxy, 1-ethoxy-propyloxy and2-methoxy-butoxy.

As used herein, the term “C₁₋₄alkoxy-C₁₋₄alkylthio” refers to a radicalof the formula —S—R_(a)—O—R_(a) where each R_(a) is independently aC₁₋₄alkyl radical as defined above. The oxygen and sulfur atoms may bebonded to any alkyl radical carbon atom. Examples ofC₁₋₄alkoxy-C₁₋₄alkylthio include methoxy-methylthio, methoxy-ethylthio,ethoxy-ethylthio, 1-ethoxy-propylthio and 2-methoxy-butylthio.

As used herein, the term “C₁₋₄alkoxy-C₂₋₄alkenyl” refers to a radical ofthe formula —R_(b)—O—R_(a) where R_(a) is a C₁₋₄alkyl radical as definedabove and R_(b) is a C₂₋₄alkenyl radical as defined above. The oxygenatom may be bonded to any carbon atom in the alkyl radical and anycarbon atom in the alkenyl radical. Examples of C₁₋₄alkoxy-C₂₋₄alkenylinclude methoxy-ethenyl, ethoxy-ethenyl, 3-methoxy-propenyl,1-ethoxy-propenyl and 2-methoxy-butenyl.

As used herein, the term “C₁₋₄alkoxy-C₂₋₄alkynyl” refers to a radical ofthe formula —R_(b)—O—R_(a) where R_(a) is a C₁₋₄alkyl radical as definedabove and R_(b) is a C₂₋₄alkynyl radical as defined above. The oxygenatom may be bonded to any carbon atom in the alkyl radical and anyavailable carbon atom in the alkynyl radical. Examples ofC₁₋₄alkoxy-C₂₋₄alkynyl include methoxy-ethynyl, ethoxy-ethynyl,3-methoxy-propynyl, 1-ethoxy-propynyl and 2-methoxy-butynyl.

The term “halogen” refers to bromo, chloro, fluoro or iodo.

As used herein, the term “halogen-C₁₋₄alkyl” refers to a C₁₋₄alkylradical, as defined above, substituted by one or more halo radicals, asdefined above. Examples of halogen-C₁₋₄alkyl include trifluoromethyl,difluoromethyl, fluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl,1-fluoromethyl-2-fluoroethyl, 3-bromo-2-fluoropropyl and1-bromomethyl-2-bromoethyl. The term “halogen-C₁₋₃alkyl” is to beconstrued accordingly.

As used herein, the term “halogen-C₁₋₄alkylthio” refers to a radical ofthe formula —S—R_(a) where R_(a) is a halogen-C₁₋₄alkyl radical asdefined above. Examples of halogen-C₁₋₄alkylthio includetrifluoromethylthio, difluoromethylthio, fluoromethylthio,trichloromethylthio, 2,2,2-trifluoroethylthio,1-fluoromethyl-2-fluoroethylthio, 3-bromo-2-fluoropropylthio and1-bromomethyl-2-bromoethylthio.

As used herein, the term “halogen-C₁₋₄alkoxy” refers to a C₁₋₄alkoxyradical, as defined above, substituted by one or more halo radicals, asdefined above. Examples of halogen-C₁₋₄alkoxy include trifluoromethoxy,difluoromethoxy, fluoromethoxy, trichloromethoxy, 2,2,2-trifluoroethoxy,1-fluoromethyl-2-fluoroethoxy, 3-bromo-2-fluoropropoxy and1-bromomethyl-2-bromoethoxy.

As used herein, the term “heteroaryl” refers to a 5- or 6-memberedaromatic monocyclic ring radical which comprises 1, 2, 3 or 4heteroatoms individually selected from nitrogen, oxygen and sulfur. Theheteroaryl radical may be bonded via a carbon atom or heteroatom.Examples of heteroaryl include furyl, pyrrolyl, thienyl, pyrazolyl,imidazolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, triazolyl,tetrazolyl, pyrazinyl, pyridazinyl, pyrimidyl and pyridyl.

As used herein, the term “hydroxyC₁₋₄alkyl” refers to a C₁₋₄alkylradical as defined above, wherein one of the hydrogen atoms of theC₁₋₄alkyl radical is replaced by OH. Examples of hydroxyC₁₋₄alkylinclude hydroxy-methyl, 2-hydroxy-ethyl, 2-hydroxy-propyl,3-hydroxy-propyl and 2-hydroxy-butyl.

As used herein, the term “hydroxyC₂₋₄alkenyl” refers to a C₂₋₄alkenylradical as defined above, wherein one of the hydrogen atoms of theC₂₋₄alkenyl radical is replaced by OH. Examples of hydroxyC₁₋₄alkenylinclude 2-hydroxy-ethenyl, 2-hydroxy-propenyl, 3-hydroxy-propenyl and2-hydroxy-butenyl.

As used herein, the term “hydroxyC₂₋₄alkynyl” refers to a C₂₋₄alkynylradical as defined above, wherein one of the hydrogen atoms of theC₂₋₄alkynyl radical is replaced by OH. Examples of hydroxyC₁₋₄alkynylinclude 2-hydroxy-ethynyl, 3-hydroxy-propynyl and 2-hydroxy-butynyl.

As used herein, the term “a,” “an,” “the” and similar terms used in thecontext of the present invention (especially in the context of theclaims) are to be construed to cover both the singular and plural unlessotherwise indicated herein or clearly contradicted by the context. Theuse of any and all examples, or exemplary language (e.g. “such as”)provided herein is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention otherwiseclaimed.

The term “compounds of the present invention” (unless specificallyidentified otherwise) refers to compounds of formula (I), (Ia), (Ib) or(Ic), compounds of the Examples, pharmaceutically acceptable salts ofsuch compounds, and/or hydrates or solvates of such compounds, as wellas, all stereoisomers (including diastereoisomers and enantiomers),tautomers and isotopically labeled compounds (including deuterium). Theterm “agents of the invention” is intended to have the same meaning as“compounds of the present invention”.

As used herein, the term “inhibit”, “inhibition” or “inhibiting” refersto the reduction or suppression of a given condition, symptom, ordisorder, or disease, or a significant decrease in the baseline activityof a biological activity or process.

As used herein, the term “pharmaceutically acceptable carrier” includesany and all solvents, dispersion media, coatings, surfactants,antioxidants, preservatives (e.g., antibacterial agents, antifungalagents), isotonic agents, absorption delaying agents, salts,preservatives, drugs, drug stabilizers, binders, excipients,disintegration agents, lubricants, sweetening agents, flavoring agents,dyes, and the like and combinations thereof, as would be known to thoseskilled in the art (see, for example, Remington's PharmaceuticalSciences, 18th Ed. Mack Printing Company, 1990, pp. 1289-1329). Exceptinsofar as any conventional carrier is incompatible with the activeingredient, its use in the therapeutic or pharmaceutical compositions iscontemplated.

As used herein, the term “prevention” of any particular disease ordisorder refers to the administration of a compound of the invention toa subject before any symptoms of that disease or disorder are apparent.

As used herein, the term “subject” refers to an animal. Typically theanimal is a mammal. A subject also refers to for example, primates(e.g., humans, male or female), cows, sheep, goats, horses, dogs, cats,rabbits, rats, mice, fish, birds and the like. In certain embodiments,the subject is a primate. In yet other embodiments, the subject is ahuman.

As used herein, a subject is “in need of” a treatment if such subjectwould benefit biologically, medically or in quality of life from suchtreatment.

The term “a therapeutically effective amount” of a compound of thepresent invention refers to an amount of the compound of the presentinvention that will elicit the biological or medical response of asubject, for example, reduction or inhibition of an enzyme or a proteinactivity, or ameliorate symptoms, alleviate conditions, slow or delaydisease progression, or prevent a disease, etc. In one non-limitingembodiment, the term “a therapeutically effective amount” refers to theamount of the compound of the present invention that, when administeredto a subject, is effective to (1) at least partially alleviating,inhibiting, preventing and/or ameliorating a condition, or a disorder ora disease (i) mediated by BACE-1 or (ii) associated with BACE-1activity, or (iii) characterized by activity (normal or abnormal) ofBACE-1; or (2) reducing or inhibiting the activity of BACE-1. In anothernon-limiting embodiment, the term “a therapeutically effective amount”refers to the amount of the compound of the present invention that, whenadministered to a cell, or a tissue, or a non-cellular biologicalmaterial, or a medium, is effective to at least partially reduce orinhibit the activity of BACE-1. The meaning of the term “atherapeutically effective amount” as illustrated in the aboveembodiments for BACE-1 also applies by the same means to any otherrelevant proteins/peptides/enzymes, such as BACE-2, or cathepsin D.

As used herein, the term “treat”, “treating” or “treatment” of anydisease or disorder refers in one embodiment, to ameliorating thedisease or disorder (i.e., slowing or arresting or reducing thedevelopment of the disease or at least one of the clinical symptomsthereof). In another embodiment, “treat”, “treating” or “treatment”refers to modulating the disease or disorder, either physically, (e.g.,stabilization of a discernible symptom), physiologically, (e.g.,stabilization of a physical parameter), or both.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides compounds and pharmaceutical compositionsthereof that may be useful in the treatment or prevention of diseases,conditions and/or disorders modulated by BACE inhibition.

Embodiment 1

A compound of formula (I), or a pharmaceutically acceptable saltthereof, as defined above in the first aspect of the invention.

Embodiment 2

A compound of formula (I), or a pharmaceutically acceptable saltthereof, as defined above in the second aspect of the invention.

Embodiment 3

A compound of formula (I), or a pharmaceutically acceptable saltthereof, as defined above in the third aspect of the invention.

Embodiment 4

A compound according to any one of Embodiments 1 to 3, or apharmaceutically acceptable salt thereof, wherein R¹ and R² areindependently hydrogen or fluoro.

Embodiment 5

A compound according to any one of Embodiments 1 to 4, or apharmaceutically acceptable salt thereof, wherein R¹ and R² are bothfluoro.

Embodiment 6

A compound according to any one of Embodiments 1 to 5, or apharmaceutically acceptable salt thereof, wherein R³ and R⁴ areindependently hydrogen or methyl.

Embodiment 7

A compound according to any one of Embodiments 1 to 6, or apharmaceutically acceptable salt thereof, wherein R³ and R⁴ are bothhydrogen.

Embodiment 8

A compound according to any one of Embodiments 1 to 7, or apharmaceutically acceptable salt thereof, wherein R⁵ is methyl,fluoromethyl, difluoromethyl, methoxymethyl, methoxyethyl, ethoxymethylor ethoxyethyl.

Embodiment 9

A compound according to any one of Embodiments 1 to 8, or apharmaceutically acceptable salt thereof, wherein R⁵ is methyl.

Embodiment 10

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is phenyl or a 5-or 6-membered monocyclic heteroaryl comprising 1, 2, 3 or 4 heteroatomsindependently selected from N, 0 and S, and wherein said phenyl orheteroaryl is optionally substituted by 1, 2, 3 or 4 substituentsindependently selected from halogen, cyano, amino, hydroxy, C₁₋₄alkyl,halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 11

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a 6-memberedmonocyclic heteroaryl comprising 1, 2, 3 or 4 heteroatoms independentlyselected from N, O and S, and wherein said phenyl or heteroaryl isoptionally substituted by 1, 2, 3 or 4 substituents independentlyselected from halogen, cyano, amino, hydroxy, C₁₋₄alkyl,halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 12

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridyl orpyrazinyl group which is optionally substituted by 1, 2 or 3substituents independently selected from halogen, cyano, amino, hydroxy,C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 13

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridyl orpyrazinyl group which is optionally substituted by 1, 2 or 3substituents independently selected from halogen, cyano, amino, hydroxy,C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy,C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl.

Embodiment 14

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridin-2-ylgroup or a pyrazin-2-yl group which is substituted by 2 substituents andwherein one of the substituents is located at the para position and oneof the substituents is located at the ortho position of the pyridin-2-ylor pyrazin-2-yl group relative to the amide linker and wherein thesubstituents are independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl.

Embodiment 15

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridin-2-ylgroup which is substituted by 2 substituents and wherein one of thesubstituents is located at the para position and one of the substituentsis located at the ortho position of the pyridin-2-yl group relative tothe amide linker and wherein the substituents are independently selectedfrom halogen, cyano, amino, hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl,halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy, C₁₋₄alkoxy,C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 16

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridin-2-ylgroup which is substituted by 2 substituents and wherein one of thesubstituents is located at the para position and one of the substituentsis located at the ortho position of the pyridin-2-yl group relative tothe amide linker and wherein the substituents are independently selectedfrom halogen, cyano, amino, hydroxy, methyl, trifluoromethyl, methoxy,trifluoromethoxy, 3-fluoro-propoxy, fluoromethoxy, 3-methoxy-propynyl,2-methoxy-ethoxy and 3-hydroxy-propynyl.

Embodiment 17

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridin-2-ylgroup which is substituted by 2 substituents and wherein one of thesubstituents is located at the para position and one of the substituentsis located at the ortho position of the pyridin-2-yl group relative tothe amide linker and wherein the substituents are independently selectedfrom halogen, cyano, amino, hydroxy, methyl, trifluoromethyl, methoxyand trifluoromethoxy.

Embodiment 18

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyrazin-2-ylgroup which is substituted by 2 substituents and wherein one of thesubstituents is located at the para position and one of the substituentsis located at the ortho position of the pyrazin-2-yl group relative tothe amide linker and wherein the substituents are independently selectedfrom halogen, cyano, amino, hydroxy, methyl, trifluoromethyl, methoxy,trifluoromethoxy, 3-fluoro-propoxy, fluoromethoxy, 3-methoxy-propynyl,2-methoxy-ethoxy and 3-hydroxy-propynyl.

Embodiment 19

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is5-cyano-3-methyl-pyridin-2-yl.

Embodiment 20

A compound according to any one of Embodiments 1 to 9, or apharmaceutically acceptable salt thereof, wherein R⁶ is3-chloro-5-trifluoromethyl-pyridin-2-yl.

Embodiment 21

A compound according to Embodiment 3 of formula (Ia), or apharmaceutically acceptable salt thereof,

whereinR¹ and R² are independently hydrogen or halogen;R³ and R⁴ are independently hydrogen or C₁₋₃alkyl; or R³ and R⁴ takentogether are cyclopropyl;R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl; andR⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising 1,2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy and C₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 22

A compound according to Embodiment 3 of formula (Ib), or apharmaceutically acceptable salt thereof,

whereinR³ and R⁴ are independently hydrogen or methyl; andR⁶ is a 6-membered monocyclic heteroaryl comprising 1, 2, 3 or 4heteroatoms independently selected from N, O and S, and wherein saidphenyl or heteroaryl is optionally substituted by 1, 2, 3 or 4substituents independently selected halogen, cyano, amino, hydroxy,C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.

Embodiment 23

A compound according to Embodiment 3 of formula (Ic), or apharmaceutically acceptable salt thereof,

whereinR⁶ is a pyridin-2-yl group which is substituted by 2 substituents andwherein one of the substituents is located at the para position and oneof the substituents is located at the ortho position of the pyridin-2-ylgroup relative to the amide linker and wherein the substituents areindependently selected from halogen, cyano, amino, hydroxy, methyl,trifluoromethyl, methoxy and trifluoromethoxy.

Embodiment 24

A compound according to Embodiment 3 of formula (Ic), or apharmaceutically acceptable salt thereof,

whereinR⁶ is a pyrazin-2-yl group which is substituted by 2 substituents andwherein one of the substituents is located at the para position and oneof the substituents is located at the ortho position of the pyrazin-2-ylgroup relative to the amide linker and wherein the substituents areindependently selected from halogen, cyano, amino, hydroxy, methyl,trifluoromethyl, methoxy and trifluoromethoxy.

Embodiment 25

A compound according to Embodiment 2, which is selected from:

-   5-Cyano-3-methyl-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-cyano-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-cyano-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Cyano-3-methyl-pyridine-2-carboxylic acid    {6-[2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;-   3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid    {6-[2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;-   3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-trifluoromethyl-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3,5-Dichloro-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2,2,2-trifluoro-ethoxy)pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2,2-difluoro-ethoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(3-fluoro-propoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Methoxy-3-methyl-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   3-Amino-5-fluoromethoxy-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-methoxy-ethoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-fluoro-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-chloro-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   3-Chloro-pyridine-2-carboxylic    acid[6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(3-methoxy-prop-1-ynyl)pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-difluoromethyl-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-chloro-ethoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-ethoxy-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   3-Amino-5-(penta-deutero-ethoxy)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   4-Chloro-1-difluoromethyl-1H-pyrazole-3-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   3-Amino-5-difluoromethyl-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Cyano-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;    and-   3-Amino-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid    [6-(2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;    and pharmaceutically acceptable salts thereof.

Embodiment 26

A compound according to Embodiment 2, which is selected from:

-   5-Cyano-3-methyl-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-cyano-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-cyano-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Cyano-3-methyl-pyridine-2-carboxylic acid    {6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;-   3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid    {6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;-   3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-trifluoromethyl-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3,5-Dichloro-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2,2,2-trifluoro-ethoxy)pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2,2-difluoro-ethoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(3-fluoro-propoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Methoxy-3-methyl-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-fluoromethoxy-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-methoxy-ethoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-fluoro-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-chloro-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-pyridine-2-carboxylic    acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(3-methoxy-prop-1-ynyl)pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-difluoromethyl-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-chloro-ethoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-ethoxy-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(penta-deutero-ethoxy)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;-   4-Chloro-1-difluoromethyl-1H-pyrazole-3-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-5-difluoromethyl-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   5-Cyano-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;-   3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;    and-   3-Amino-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid    [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;    and pharmaceutically acceptable salts thereof.

On account of one or more than one asymmetrical carbon atom, which maybe present in a compound of the formula (I), a corresponding compound ofthe formula (I) may exist in pure optically active form or in the formof a mixture of optical isomers, e.g. in the form of a racemic mixture.All of such pure optical isomers and all of their mixtures, includingthe racemic mixtures, are part of the present invention unless thecontext dictates otherwise (for example in an embodiment of theinvention clearly specifying a single enantiomer).

As used herein, the term “isomers” refers to different compounds thathave the same molecular formula but differ in arrangement andconfiguration of the atoms. Also as used herein, the term “an opticalisomer” or “a stereoisomer” refers to any of the various stereo isomericconfigurations which may exist for a given compound of the presentinvention and includes geometric isomers. It is understood that asubstituent may be attached at a chiral center of a carbon atom. Theterm “chiral” refers to molecules which have the property ofnon-superimposability on their mirror image partner, while the term“achiral” refers to molecules which are superimposable on their mirrorimage partner. Therefore, unless the context dictates otherwise (forexample in an embodiment of the invention clearly specifying a singleenantiomer) the invention includes enantiomers, diastereomers orracemates of the compound. “Enantiomers” are a pair of stereoisomersthat are non-superimposable mirror images of each other. A 1:1 mixtureof a pair of enantiomers is a “racemic” mixture. The term is used todesignate a racemic mixture where appropriate. “Diastereoisomers” arestereoisomers that have at least two asymmetric atoms, but which are notmirror-images of each other. The absolute stereochemistry is specifiedaccording to the Cahn-Ingold-Prelog R-S system. When a compound is apure enantiomer the stereochemistry at each chiral carbon may bespecified by either R or S. Resolved compounds whose absoluteconfiguration is unknown can be designated (+) or (−) depending on thedirection (dextro- or levorotatory) which they rotate plane polarizedlight at the wavelength of the sodium D line. Certain compoundsdescribed herein contain one or more asymmetric centers or axes and maythus give rise to enantiomers, diastereomers, and other stereoisomericforms that may be defined, in terms of absolute stereochemistry, as (R)-or (S)-.

Depending on the choice of the starting materials and procedures, thecompounds can be present in the form of one of the possible isomers oras mixtures thereof, for example as pure optical isomers, or as isomermixtures, such as racemates and diastereoisomer mixtures, depending onthe number of asymmetric carbon atoms. The present invention is meant toinclude all such possible isomers, including racemic mixtures,diasteriomeric mixtures and optically pure forms. Optically active (R)-and (S)-isomers may be prepared using chiral synthons or chiralreagents, or resolved using conventional techniques. If the compoundcontains a double bond, the substituent may be E or Z configuration. Ifthe compound contains a disubstituted cycloalkyl, the cycloalkylsubstituent may have a cis- or trans-configuration.

In one embodiment of the invention, there is provided a compound of theExamples having one chiral center as an isolated stereoisomer in the Rconfiguration.

In one embodiment of the invention, there is provided a compound of theExamples having one chiral center as an isolated stereoisomer in the Sconfiguration.

In one embodiment of the invention, there is provided a compound of theExamples having one chiral center as a racemic mixture.

It is also possible that the intermediates and compounds of the presentinvention may exist in different tautomeric forms, and all such formsare embraced within the scope of the invention. The term “tautomer” or“tautomeric form” refers to structural isomers of different energieswhich are interconvertible via a low energy barrier. For example, protontautomers (also known as prototropic tautomers) include interconversionsvia migration of a proton, such as keto-enol and imine-enamineisomerizations. A specific example of a proton tautomer is the imidazolemoiety where the proton may migrate between the two ring nitrogens.Valence tautomers include interconversions by reorganization of some ofthe bonding electrons.

Any resulting mixtures of isomers can be separated on the basis of thephysicochemical differences of the constituents, into the pure orsubstantially pure geometric or optical isomers, diastereomers,racemates, for example, by chromatography and/or fractionalcrystallization.

Any resulting racemates of final products or intermediates can beresolved into the optical antipodes by known methods, e.g., byseparation of the diastereomeric salts thereof, obtained with anoptically active acid or base, and liberating the optically activeacidic or basic compound. In particular, a basic moiety may thus beemployed to resolve the compounds of the present invention into theiroptical antipodes, e.g., by fractional crystallization of a salt formedwith an optically active acid, e.g., tartaric acid, dibenzoyl tartaricacid, diacetyl tartaric acid, di-O,O′-p-toluoyl tartaric acid, mandelicacid, malic acid or camphor-10-sulfonic acid. Racemic products can alsobe resolved by chiral chromatography, e.g., high pressure liquidchromatography (HPLC) using a chiral adsorbent.

As used herein, the terms “salt” or “salts” refers to an acid additionsalt of a compound of the invention. “Salts” include in particular“pharmaceutical acceptable salts”. The term “pharmaceutically acceptablesalts” refers to salts that retain the biological effectiveness andproperties of the compounds of this invention and, which typically arenot biologically or otherwise undesirable. The compounds of the presentinvention may be capable of forming acid salts by virtue of the presenceof amino groups or groups similar thereto.

In one embodiment, the invention relates to a compound of the formula(I), (Ia), (Ib) or (Ic) as defined herein, in free form. In anotherembodiment, the invention relates to a compound of the formula (I),(Ia), (Ib) or (Ic) as defined herein, in salt form. In anotherembodiment, the invention relates to a compound of the formula (I),(Ia), (Ib) or (Ic) as defined herein, in acid addition salt form. In afurther embodiment, the invention relates to a compound of the formula(I), (Ia), (Ib) or (Ic) as defined herein, in pharmaceuticallyacceptable salt form. In yet a further embodiment, the invention relatesto a compound of the formula (I), (Ia), (Ib) or (Ic) as defined herein,in pharmaceutically acceptable acid addition salt form. In yet a furtherembodiment, the invention relates to a compound of the formula (I),(Ia), (Ib) or (Ic) as defined herein, in hydrochloride salt form. In yeta further embodiment, the invention relates to any one of the compoundsof the Examples in free form. In yet a further embodiment, the inventionrelates to any one of the compounds of the Examples in salt form. In yeta further embodiment, the invention relates to any one of the compoundsof the Examples in acid addition salt form. In yet a further embodiment,the invention relates to any one of the compounds of the Examples inpharmaceutically acceptable salt form. In still another embodiment, theinvention relates to any one of the compounds of the Examples inpharmaceutically acceptable acid addition salt form. In still anotherembodiment, the invention relates to any one of the compounds of theExamples in hydrochloride salt form.

Pharmaceutically acceptable acid addition salts can be formed withinorganic acids and organic acids, e.g., acetate, aspartate, benzoate,besylate, bromide/hydrobromide, bicarbonate/carbonate,bisulfate/sulfate, camphorsulfonate, chloride/hydrochloride,chlortheophyllonate, citrate, ethandisulfonate, fumarate, gluceptate,gluconate, glucuronate, hippurate, hydroiodide/iodide, isethionate,lactate, lactobionate, laurylsulfate, malate, maleate, malonate,mandelate, mesylate, methylsulphate, naphthoate, napsylate, nicotinate,nitrate, octadecanoate, oleate, oxalate, palmitate, pamoate,phosphate/hydrogen phosphate/dihydrogen phosphate, polygalacturonate,propionate, stearate, succinate, sulfosalicylate, tartrate, tosylate andtrifluoroacetate salts.

Inorganic acids from which salts can be derived include, for example,hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid,phosphoric acid, and the like.

Organic acids from which salts can be derived include, for example,acetic acid, propionic acid, glycolic acid, oxalic acid, maleic acid,malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid,benzoic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid,toluenesulfonic acid, sulfosalicylic acid, and the like.Pharmaceutically acceptable base addition salts can be formed withinorganic and organic bases.

The pharmaceutically acceptable salts of the present invention can besynthesized from an acidic moiety, by conventional chemical methods.Generally, such salts can be prepared by reacting free base forms ofthese compounds with a stoichiometric amount of the appropriate acid.Such reactions are typically carried out in water or in an organicsolvent, or in a mixture of the two. Generally, use of non-aqueous medialike ether, ethyl acetate, ethanol, isopropanol, or acetonitrile isdesirable, where practicable. Lists of additional suitable salts can befound, e.g., in “Remington's Pharmaceutical Sciences”, 20th ed., MackPublishing Company, Easton, Pa., (1985); and in “Handbook ofPharmaceutical Salts: Properties, Selection, and Use” by Stahl andWermuth (Wiley-VCH, Weinheim, Germany, 2002).

Furthermore, the compounds of the present invention, including theirsalts, may also be obtained in the form of their hydrates, or includeother solvents used for their crystallization. The compounds of thepresent invention may inherently or by design form solvates withpharmaceutically acceptable solvents (including water); therefore, it isintended that the invention embrace both solvated and unsolvated forms.The term “solvate” refers to a molecular complex of a compound of thepresent invention (including pharmaceutically acceptable salts thereof)with one or more solvent molecules. Such solvent molecules are thosecommonly used in the pharmaceutical art, which are known to be innocuousto the recipient, e.g., water, ethanol, and the like. The term “hydrate”refers to the complex where the solvent molecule is water.

Compounds of the invention, i.e. compounds of formula (I) that containgroups capable of acting as donors and/or acceptors for hydrogen bondsmay be capable of forming co-crystals with suitable co-crystal formers.These co-crystals may be prepared from compounds of formula (I) by knownco-crystal forming procedures. Such procedures include grinding,heating, co-subliming, co-melting, or contacting in solution compoundsof formula (I) with the co-crystal former under crystallizationconditions and isolating co-crystals thereby formed. Suitable co-crystalformers include those described in WO 2004/078163. Hence the inventionfurther provides co-crystals comprising a compound of formula (I).

The compounds of the present invention, including salts, hydrates andsolvates thereof, may inherently or by design form polymorphs.

Any formula given herein is also intended to represent unlabeled formsas well as isotopically labeled forms of the compounds. Isotopicallylabeled compounds have structures depicted by the formulas given hereinexcept that one or more atoms are replaced by an atom having a selectedatomic mass or mass number. Examples of isotopes that can beincorporated into compounds of the invention include isotopes ofhydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine, and chlorine,such as ²H, ³H, ¹¹C, ¹³C, ¹⁴C, ¹⁵N, ¹⁸F ³¹P, ³²P, ³⁵S, ³⁶Cl, ¹²⁵Irespectively. The invention includes various isotopically labeledcompounds as defined herein, for example those into which radioactiveisotopes, such as ³H and ¹⁴C, or those into which non-radioactiveisotopes, such as ²H and ¹³C are present. Such isotopically labelledcompounds are useful in metabolic studies (with ¹⁴C), reaction kineticstudies (with, for example ²H or ³H), detection or imaging techniques,such as positron emission tomography (PET) or single-photon emissioncomputed tomography (SPECT) including drug or substrate tissuedistribution assays, or in radioactive treatment of patients. Inparticular, an ¹⁸F or labeled compound may be particularly desirable forPET or SPECT studies. Isotopically-labeled compounds of formula (I) cangenerally be prepared by conventional techniques known to those skilledin the art or by processes analogous to those described in theaccompanying Examples and Preparations using an appropriateisotopically-labeled reagents in place of the non-labeled reagentpreviously employed.

Further, substitution with heavier isotopes, particularly deuterium(i.e., ²H or D) may afford certain therapeutic advantages resulting fromgreater metabolic stability, for example increased in vivo half-life orreduced dosage requirements or an improvement in therapeutic index. Itis understood that deuterium in this context is regarded as asubstituent of a compound of the formula (I). The concentration of sucha heavier isotope, specifically deuterium, may be defined by theisotopic enrichment factor. The term “isotopic enrichment factor” asused herein means the ratio between the isotopic abundance and thenatural abundance of a specified isotope. If a substituent in a compoundof this invention is denoted deuterium, such compound has an isotopicenrichment factor for each designated deuterium atom of at least 3500(52.5% deuterium incorporation at each designated deuterium atom), atleast 4000 (60% deuterium incorporation), at least 4500 (67.5% deuteriumincorporation), at least 5000 (75% deuterium incorporation), at least5500 (82.5% deuterium incorporation), at least 6000 (90% deuteriumincorporation), at least 6333.3 (95% deuterium incorporation), at least6466.7 (97% deuterium incorporation), at least 6600 (99% deuteriumincorporation), or at least 6633.3 (99.5% deuterium incorporation).

Pharmaceutically acceptable solvates in accordance with the inventioninclude those wherein the solvent of crystallization may be isotopicallysubstituted, e.g. D₂O, d₆-acetone, d₆-DMSO.

Compounds of the present invention may be synthesized by syntheticroutes that include processes analogous to those well-known in thechemical arts, particularly in light of the description containedherein. The starting materials are generally available from commercialsources such as Sigma-Aldrich or are readily prepared using methods wellknown to those skilled in the art (e.g., prepared by methods generallydescribed in Louis F. Fieser and Mary Fieser, Reagents for OrganicSynthesis, v. 1-19, Wiley, New York (1967-1999 ed.), or BeilsteinsHandbuch der organischen Chemie, 4, Aufl. ed. Springer-Verlag, Berlin,including supplements (also available via the Beilstein onlinedatabase)).

For illustrative purposes, reaction schemes 1 and 2 depicted belowprovide potential routes for synthesizing the compounds of the presentinvention as well as key intermediates. For a more detailed descriptionof the individual reaction steps, see the Examples section below. Thoseskilled in the art will appreciate that other synthetic routes may beused to synthesize the inventive compounds. Although specific startingmaterials and reagents are depicted in the schemes and discussed below,other starting materials and reagents can be easily substituted toprovide a variety of derivatives and/or reaction conditions. Inaddition, many of the compounds prepared by the methods described belowcan be further modified in light of this disclosure using conventionalchemistry well known to those skilled in the art.

In a further aspect, the invention relates to a process for thepreparation of a compound of the formula (I), in free form or inpharmaceutically acceptable salt form, comprising

a) the reaction of a compound of the formula

in free form or in salt form, in which R¹, R², R³, R⁴ and R⁵ are asdefined for the formula I and PG is a protecting group, for exampleN-tert-butoxycarbonyl, with a compound of the formula

in free form or in salt form, in which R⁶ is as defined for the formulaI and L is a leaving group, for example a hydroxyl group,

b) the reaction of a compound of the formula

in free form or in salt form, in which R¹, R², R³, R⁴ and R⁵ are asdefined for the formula I, Hal is halogen, for example bromine, and PGis a protecting group, for example N-tert-butoxycarbonyl, with acompound of the formula

in free form or in salt form, in which R⁶ is as defined for the formulaI,

c) the optional reduction, oxidation or other functionalisation of theresulting compound,

d) the cleavage of any protecting group(s) optionally present and

e) the recovery of the so obtainable compound of the formula I in freeform or in salt form.

The above reactions can be effected according to conventional methods.For example, the reaction described in step (a) may be carried out inthe presence of a suitable coupling agent, for example1-hydroxy-7-azabenzotriazole, a suitable activating agent, for example1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, andoptionally a suitable base, for example diisopropylethylamine, asuitable solvent, for example dimethylformamide, and at a suitabletemperature, for example 0 to 50° C., more suitably 0 to 25° C.

The reaction described in step (b) may be carried out:

(i) in the presence of a suitable catalyst, for exampletris(dibenzylidene-acetone) di palladium, a suitable ligand, for exampleXantphos, a suitable base, for example cesium carbonate, a suitablesolvent, for example dioxane, and at a suitable temperature, for example10 to 100° C., more suitably 30 to 85° C.; or

(ii) in the presence of a suitable catalyst, for example copper iodide,a suitable ligand, for examplerac-trans-N,N′-dimethylcyclohexane-1,2-diamine, a suitable base, forexample potassium carbonate, a suitable solvent, for example dioxane,and at a suitable temperature, for example reflux temperature.

The starting materials of the formulae II, IIa, III and IIIa are knownor may be prepared according to conventional procedures starting fromknown compounds, may be prepared from known compounds as described inthe Examples, or may be prepared using procedures analogous to thosedescribed in the Examples.

The further optional reduction, oxidation or other functionalisation ofcompounds of formula (I) may be carried out according to methods wellknow to those skilled in the art.

Within the scope of this text, only a readily removable group that isnot a constituent of the particular desired end product of the compoundsof the present invention is designated a “protecting group”, unless thecontext indicates otherwise. The protection of functional groups by suchprotecting groups, the protecting groups themselves, and their cleavagereactions are described for example in standard reference works, such asJ. F. W. McOmie, “Protective Groups in Organic Chemistry”, Plenum Press,London and New York 1973, in T. W. Greene and P. G. M. Wuts, “ProtectiveGroups in Organic Synthesis”, Third edition, Wiley, New York 1999, in“The Peptides”; Volume 3 (editors: E. Gross and J. Meienhofer), AcademicPress, London and New York 1981, in “Methoden der organischen Chemie”(Methods of Organic Chemistry), Houben Weyl, 4th edition, Volume 15/I,Georg Thieme Verlag, Stuttgart 1974, and in H.-D. Jakubke and H.Jeschkeit, “Aminosauren, Peptide, Proteine” (Amino acids, Peptides,Proteins), Verlag Chemie, Weinheim, Deerfield Beach, and Basel 1982. Acharacteristic of protecting groups is that they can be removed readily(i.e. without the occurrence of undesired secondary reactions) forexample by solvolysis, reduction, photolysis or alternatively underphysiological conditions (e.g. by enzymatic cleavage).

Salts of compounds of the present invention having at least onesalt-forming group may be prepared in a manner known to those skilled inthe art. For example, acid addition salts of compounds of the presentinvention are obtained in customary manner, e.g. by treating thecompounds with an acid or a suitable anion exchange reagent.

Salts can be converted into the free compounds in accordance withmethods known to those skilled in the art. Acid addition salts can beconverted, for example, by treatment with a suitable basic agent.

For those compounds containing an asymmetric carbon atom, the compoundsexist in individual optically active isomeric forms or as mixturesthereof, e.g. as racemic or diastereomeric mixtures. Diastereomericmixtures can be separated into their individual diastereoisomers on thebasis of their physical chemical differences by methods well known tothose skilled in the art, such as by chromatography and/or fractionalcrystallization. Enantiomers can be separated by converting theenantiomeric mixture into a diastereomeric mixture by reaction with anappropriate optically active compound (e.g., chiral auxiliary such as achiral alcohol or Mosher's acid chloride), separating thediastereoisomers and converting (e.g., hydrolyzing) the individualdiastereoisomers to the corresponding pure enantiomers. Enantiomers canalso be separated by use of a commercially available chiral HPLC column.

The invention further includes any variant of the present processes, inwhich the reaction components are used in the form of their salts oroptically pure material. Compounds of the invention and intermediatescan also be converted into each other according to methods generallyknown to those skilled in the art.

Compounds of the formula (I), in free form or in pharmaceuticallyacceptable salt form, herein-after often referred to as “agents of theinvention”, exhibit valuable pharmacological properties, when tested invitro, and may, therefore, be useful in medicaments, in therapy or foruse as research chemicals, for example as tool compounds.

For example, agents of the invention are inhibitors of BACE-1 and BACE-2and may be used for the treatment or prevention of a condition, diseaseor disorder involving processing by such enzymes, particularly thegeneration of beta-amyloid and the subsequent aggregation into oligomersand fibrils, and loss of β cell mass and/or function.

The inhibiting properties of an agent of the invention towards proteasescan be evaluated in the tests as described hereinafter.

Test 1: Inhibition of Human BACE-1

Recombinant BACE-1 (extracellular domain, expressed in baculovirus andpurified using standard methods) at 0.1 to 1 nM concentrations isincubated with the test compound at various concentrations for 1 hour atroom temperature in 100 mM acetate buffer, pH 4.5, containing 0.1%CHAPS. Activity was measured using a final concentration of 3 μM of thefluorescence-quenched substrateQ-C(HSO₃)-Ile-Asp-Leu-Ala-Val-Leu-Asp-HN-CH₂-CH₂-Mca, whereQ=2-nitro-5-amino benzoic acid and Mca=7-methoxy-4-coumarinyl aceticacid. Catalytic turnover was monitored in a Spectramax Geminifluorescence plate reader (Molecular Devices) in black 96-wellmicroplates using excitation/emission wavelength of 325 nm and 400 nm,respectively. Fluorescence increase was followed for 15 min, in 1minute's intervals. The fluorescence/time slopes were calculated fromduplicate wells and from wells without inhibitor and the IC₅₀ valueswere calculated using a logistic 4-parameter model.

Test 2: Inhibition of Human BACE-2

Recombinant BACE-2 (extracellular domain, expressed in baculovirus andpurified using standard methods) at 0.1 to 1 nM concentrations isincubated with the test compound at various concentrations for 1 hour atroom temperature in 100 mM acetate buffer, pH 4.5, containing 0.1%CHAPS. Activity was measured using a final concentration of 3 μM of thefluorescence-quenched substrateQ-C(HSO₃)-Ile-Asp-Leu-Ala-Val-Leu-Asp-HN-CH₂-CH₂-Mca, whereQ=2-nitro-5-amino benzoic acid and Mca=7-methoxy-4-coumarinyl aceticacid. Catalytic turnover was monitored in a Spectramax Geminifluorescence plate reader (Molecular Devices) in black 96-wellmicroplates using excitation/emission wavelength of 325 nm and 400 nm,respectively. Fluorescence increase was followed for 15 min, in 1minute's intervals. The fluorescence/time slopes were calculated fromduplicate wells and from wells without inhibitor and the IC₅₀ valueswere calculated using a logistic 4-parameter model.

Test 3: Inhibition of Human Cathepsin D

Recombinant cathepsin D (expressed as procathepsin D in baculovirus,purified using standard methods and activated by incubation in sodiumformate buffer pH 3.7) is incubated with the test compound at variousconcentrations for 1 hour at room temperature in sodium formate orsodium acetate buffer at a suitable pH within the range of pH 3.0 to5.0. Synthetic peptide substrateMca-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys(DNP)-D-Arg-NH₂ is added to afinal concentration of 1 to 5 μM, and the increase in fluorescence isrecorded at excitation of 325 nm and emission at 400 nm in a microplatespectro-fluorimeter for 5 to 30 minutes in 1-minute intervals. IC₅₀values are calculated from the percentage of inhibition of cathepsinD-activity as a function of the test compound concentration.

Test 4: Inhibition of Cellular Release of Amyloid Peptide 1-40

Chinese hamster ovary cells are transfected with the human gene foramyloid precursor protein. The cells are plated at a density of 8000cells/well into 96-well microtiter plates and cultivated for 24 hours inDMEM cell culture medium containing 10% FCS. The test compound is addedto the cells at various concentrations, and the cells are cultivated for24 hours in the presence of the test compound. The supernatants arecollected, and the concentration of amyloid peptide 1-40 is determinedusing state of the art immunoassay techniques, for example sandwichELISA, homogenous time-resolved fluorescence (HTRF) immunoassay, orelectro-chemiluminescence immunoassay. The potency of the compound iscalculated from the percentage of inhibition of amyloid peptide releaseas a function of the test compound concentration.

The compounds of the Examples showed the IC₅₀ values presented in Table1 below when tested in Tests 1, 2 and 4. NT=Not Tested

TABLE 1 Test 4 Example Test 1 Test 2 Amyloid-β1-40 No. BACE-1 IC₅₀ [μM]BACE-2 IC₅₀ [μM] release IC₅₀ [μM] 1 0.012 0.066 0.007 2 0.012 0.0710.008 3 0.029 0.14 0.007 4 0.1 0.58 0.049 5 >10 >10 >10 6 0.65 6.6 0.387 0.035 0.29 0.027 8 0.16 1.4 0.14 9 0.018 0.004 0.012 10 0.59 3.8 0.611 0.83 2.9 0.44 12 1.2 >10 0.31 13 0.27 0.093 0.082 14 NT NT 0.54 150.11 0.73 0.030 16 0.12 8.9 NT 17 0.24 8.2 0.062 18 0.33 0.12 0.088 190.06 0.048 0.045 20 0.36 0.095 0.088 21 0.083 0.84 0.081 22 0.19 0.580.06 23 8.7 >10 2.9 24 0.24 4.5 0.25 25 0.57 >10 0.48 26 0.11 0.0270.057 27 0.29 0.42 0.45 28 1.9 10 0.84 29 0.15 5.6 0.07 30 0.019 0.0070.013 31 0.54 0.49 0.18 32 0.06 0.93 0.019 33 0.14 0.26 0.066 34 >10 >106.5 35 0.054 0.26 0.014 36 NT NT 0.058 37 0.064 >10 0.31

Test 5: In Vivo Inhibitory Activity of Example Compounds

Male Sprague-Dawley rats, 220-280 g weight, (Charles River, France) weredosed by oral gavage with vehicle alone (0.1% Tween80, 0.5%methylcellulose in water) or with compound suspended in vehicle at adose of 10 micromoles compound per kilogram body weight, 4 hours priorto sacrifice. The 4 hour timepoint was selected in order to compare theactivity of compounds that have sufficient pharmacokinetic andbiodistribution properties to reduce total brain Abeta withinapproximately three half-lives of the rat brain Abeta40 peptide.

Immediately prior to sacrifice, anaesthetized rat (spontaneousinhalation, 2-5% Isoflurane and air) were fixed in a stereotaxicapparatus on a raised platform, with anesthesia maintained though a nosecone. The angle of the head was tilted downward, perpendicular to thebody, and a hypodermic needle lowered through the skin behind theoccipital ridge, into the Cisterna magna. Cerebrospinal fluid (CSF) waswithdrawn (˜-50-100 μL), dispensed into tubes (protein Lo-bind Eppendorftubes for Abeta40 analysis, normal Eppendorph tubes for compoundanalysis), frozen on dry ice and stored at −80° C. until analysis. Ratswere then immediately decapitated under anesthesia, trunk bloodcollected for analysis of compound levels and the brain retrieved. Onehalf-forebrain was dissected by removing the cerebellum and olfactorybulbs, frozen in three pieces on a metal plate pre-cooled on frozen CO₂and stored in tubes at −80° C. until analysis for Abeta40. For the otherhalf-brain, olfactory bulbs were discarded and a sagittal slice takenfrom the medial aspect, weighing ˜200-400 mg, placed in glass HPLC tubesand frozen on dry ice until analysis for compound levels.

Soluble Abeta40 levels in the rat brain and CSF were quantified using aMeso Scale Discovery (MSD) 96-well MULTI-ARRAY human/rodent (4G8)Abeta40 Ultrasensitive Assay (#K110FTE-3, Meso Scale Discovery,Gaithersburg, USA). Forebrain sample homogenates were prepared bysonication in 9 volumes (w/v) of ice cold TBA. Fifty μL of 2% TX-100 inTBS-complete was added to 50 μL aliquots of the homogenate to reach afinal concentration of 1% TX-100 in a 1:20 dilution. Samples wereincubated on ice for 15 min interrupted with 3 short vortexing steps,then centrifuged (100 000×g, 4° C., 15 min), and 50 μL of supernatantcollected. This was further diluted 1:5 with 3% Blocker A solution fromthe MSD kit to a final dilution of 1:100 and applied to the MSD plate.CSF samples containing blood were excluded. All other CSF samples werediluted with 1% Blocker A solution (from manufacturers kit) to reach a1:20 CSF dilution. Calibration curves were prepared in 1% Blocker Asolution spiked with synthetic Abetal-40 peptide. Samples andcalibration standards were applied in duplicate at a volume of 25 μL perwell. Abeta40 concentrations of samples were estimated from the standardcurve using SOFTmax PRO 4.0.

The compounds of Examples 2, 3, 7 and 30 of the present invention andthose of Examples 22, 39 and 71 of WO 2011/069934 A1 showed the effectspresented in Table 2 below on Abeta lowering in rat brain and CSF whentested in Test 5. (n.s.=not statistically significant (Student'st-test))

TABLE 2 Abeta Abeta lowering lowering in Example No. Structure in ratforebrain rat CSF  7 Present Invention

−63.6% −67.9% 39 WO 2011/069934 A1

−1.4% (n.s.) −8.2% (n.s.)  2 Present Invention

−67.1% −70.7% 22 WO 2011/069934 A1

−7.8% (n.s.) −17.9%  3 Present Invention

−20.0% −35.3% 71 WO 2011/069934 A1

−5.6% (n.s.) −30.4% 30 Present Invention

−46.6% −55.2%

Blood, CSF and brain samples were also analyzed for compound levelsusing liquid chromatography/tandem mass spectrometry methods (LC/MS/MS).Brain samples were mixed with 2 volumes of KH₂PO₄ buffer and homogenizedusing a Covaris® device. Either 30 or 50 μL of blood, CSF or tissuehomogenate were spiked with a structurally related internal standard andsubsequently mixed with an at least 4-fold excess volume acetonitrile(protein precipitation). The supernatant was either directly, or afterdilution with water, injected into the LC/MS/MS system for analysis.

Due to their inhibiting properties towards proteases, and BACE-1 inparticular, agents of the invention may be useful, e.g., in thetreatment or prevention of a variety of disabilitating psychiatric,psychotic, neurological or vascular states, e.g. of a condition, diseaseor disorder of the vascular system or of the nervous system, in whichbeta-amyloid generation or aggregation plays a role. Based on theinhibition of BACE-2 (beta-site APP-cleaving enzyme 2) or cathepsin D,which are close homologues of the pepsin-type aspartyl proteases andbeta-secretase, and the correlation of BACE-2 or cathepsin D expressionwith a more tumorigenic or metastatic potential of tumor cells, theagents of the invention may also be useful as anti-cancer medicaments,e.g. in the suppression of the metastasis process associated with tumorcells. Furthermore, based on the inhibition of BACE-2 and thecorrelation of BACE-2 activity with TME27 cleavage and β cell mass, theagents of the invention may also be useful for treating or preventingloss of β cell mass and/or function, e.g. in the treatment of diabetes.

The said condition, disease or disorder of the vascular system or of thenervous system is exemplified by, and includes, without limitation, ananxiety disorder, such as panic disorder with or without agoraphobia,agoraphobia without history of panic disorder, an animal or otherspecific phobia, including a social phobia, social anxiety disorder,anxiety, obsessive-compulsive disorder, a stress disorder, includingpost-traumatic or acute stress disorder, or a generalized orsubstance-induced anxiety disorder; a neurosis; seizures; epilepsy,especially partial seizures, simple, complex or partial seizuresevolving to secondarily generalized seizures or generalized seizures[absence (typical or atypical), myoclonic, clonic, tonic, tonic-clonicor atonic seizures]; convulsions; migraine; an affective disorder,including a depressive or bipolar disorder, e.g. single-episode orrecurrent major depressive disorder, major depression, a dysthymicdisorder, dysthymia, depressive disorder NOS, bipolar I or bipolar IImanic disorder or cyclothymic disorder; a psychotic disorder, includingschizophrenia or depression; neurodegeneration, e.g. neurodegenerationarising from cerebral ischemia; an acute, traumatic or chronicdegenerative process of the nervous system, such as Parkinson's disease,Down's syndrome, dementia, e.g. senile dementia, dementia with Lewybodies or a fronto-temporal dementia, a cognitive disorder, cognitiveimpairment, e.g. mild cognitive impairment, memory impairment, anamyloid neuropathy, a peripheral neuropathy, Alzheimer's disease,Gerstmann-Straeussler-Scheinker syndrome, Niemann-Pick disease, e.g.Niemann-Pick type C disease, brain inflammation, a brain, spinal cord ornerve injury, e.g. traumatic brain injury (TBI), a nerve trauma or abrain trauma, vascular amyloidosis, cerebral haemorrhage withamyloidosis, Huntington's chorea, amyotrophic lateral sclerosis,multiple sclerosis or fragile X syndrome; scrapie; cerebral amyloidangiopathy; an encephalopathy, e.g. transmissible spongiformencephalopathy; stroke; an attention disorder, e.g. attention deficithyperactivity disorder; Tourette's syndrome; a speech disorder,including stuttering; a disorder of the circadian rhythm, e.g. insubjects suffering from the effects of jet lag or shift work; pain;nociception; itch; emesis, including acute, delayed or anticipatoryemesis, such as emesis induced by chemotherapy or radiation, motionsickness, or post-operative nausea or vomiting; an eating disorder,including anorexia nervosa or bulimia nervosa; premenstrual syndrome; amuscle spasm or spasticity, e.g. in paraplegic patients; a hearingdisorder, e.g. tinnitus or age-related hearing impairment; urinaryincontinence; glaucoma; inclusion-body myositis; or a substance-relateddisorder, including substance abuse or dependency, including asubstance, such as alcohol, withdrawal disorder. Agents of the inventionmay also be useful in enhancing cognition, e.g. in a subject sufferingfrom a dementing condition, such as Alzheimer's disease; aspre-medication prior to anaesthesia or a minor medical intervention,such as endoscopy, including gastric endoscopy; or as ligands, e.g.radioligands or positron emission tomography (PET) ligands.

Due to their inhibiting properties towards BACE-2, compounds of theinvention may be useful in the treatment or prevention a disease ordisorder mediated by BACE-2. Diseases and disorders associated withBACE-2 include: metabolic syndrome (such as dyslipidemia, obesity,insulin resistance, hypertension, microalbuminemia, hyperuricaemia, andhypercoagulability), insulin resistance, glucose intolerance (also knownas impaired glucose tolerance or impaired glucose tolerance, IGT),obesity, hypertension, or diabetic complications (such as retinopathy,nephropathy, diabetic foot, ulcers, macroangiopathies, metabolicacidosis or ketosis, reactive hypoglycaemia, hyperinsulinaemia), glucosemetabolic disorder, dyslipidaemias of different origins, atherosclerosisand related diseases, high blood pressure, chronic heart failure,Syndrome X, diabetes, non-insulin-dependent diabetes mellitus, Type 2diabetes, Type 1 diabetes, body weight disorders, weight loss, body massindex and leptin related diseases.

Compounds of the invention may be suitable for preventing beta-celldegeneration such as apoptosis or necrosis of pancreatic beta cells, forimproving or restoring the functionality of pancreatic cells, and/orincreasing the number and/or size of pancreatic beta cells.

As used herein a patient is suffering from “obesity” if the patientexhibits at least one of:

-   -   a body mass index (BMI), i.e. the patient's mass (in kg) divided        by the square of the patient's height (in m), of 30 or more;    -   an absolute waist circumference of >102 cm in men or >88 cm in        women;    -   a waist-to-hip ratio >0.9 in men or >0.85 in women; or    -   a percent body fat >25% in men or >30% in women.

As used herein a patient is suffering from “Type 2 diabetes” if theymeet the World Health

Organisation criteria for Diabetes diagnosis (Definition and diagnosisof diabetes mellitus and intermediate hyperglycaemia, WHO, 2006), i.e.the patient exhibits at least one of:

-   -   a fasting plasma glucose ≧7.0 mmol/l (126 mg/dl); or    -   a venous plasma glucose 11.1 mmol/l (200 mg/dl) 2 hours after        ingestion of 75 g oral glucose load.

As used herein a patient is suffering from “IGT” if they meet the WorldHealth Organisation criteria for IGT diagnosis (Definition and diagnosisof diabetes mellitus and intermediate hyperglycaemia, WHO, 2006), i.e.the patient exhibits both of:

-   -   a fasting plasma glucose <7.0 mmol/l (126 mg/dl); and    -   a venous plasma glucose ≧7.8 and <11.1 mmol/l (200 mg/dl) 2        hours after ingestion of 75 g oral glucose load.

As used herein, the term “metabolic syndrome” is a recognized clinicalterm used to describe a condition comprising combinations of Type IIdiabetes, impaired glucose tolerance, insulin resistance, hypertension,obesity, increased abdominal girth, hypertriglyceridemia, low HDL,hyperuricaernia, hypercoagulability and/or microalbuminemia. TheAmerican Heart Association has published guidelines for the diagnosis ofmetabolic syndrome, Grundy, S., et. al., (2006) Cardiol. Rev. Vol. 13,No. 6, pp. 322-327.

For the above-mentioned indications, the appropriate dosage will varydepending on, e.g., the compound employed as active pharmaceuticalingredient, the host, the mode of administration, the nature andseverity of the condition, disease or disorder or the effect desired.However, in general, satisfactory results in animals are indicated to beobtained at a daily dosage of from about 0.1 to about 100, preferablyfrom about 1 to about 50, mg/kg of animal body weight. In largermammals, for example humans, an indicated daily dosage is in the rangeof from about 0.5 to about 2000, preferably from about 2 to about 200,mg of an agent of the invention conveniently administered, for example,in divided doses up to four times a day or in sustained release form.

An agent of the invention may be administered by any conventional route,in particular enterally, preferably orally, e.g. in the form of a tabletor capsule, or parenterally, e.g. in the form of an injectable solutionor suspension.

In a further aspect, the invention relates to a pharmaceuticalcomposition comprising an agent of the invention as activepharmaceutical ingredient in association with at least onepharmaceutically acceptable carrier or diluent and optionally inassociation with other auxiliary substances, such as inhibitors ofcytochrome P450 enzymes, agents preventing the degradation of activepharmaceutical ingredients by cytochrome P450, agents improving orenhancing the pharmacokinetics of active pharmaceutical ingredients,agents improving or enhancing the bioavailability of activepharmaceutical ingredients, and so on, e.g. grapefruit juice,ketoconazole or, preferably, ritonavir. Such a composition may bemanufactured in conventional manner, e.g. by mixing its components. Unitdosage forms contain, e.g., from about 0.1 to about 1000, preferablyfrom about 1 to about 500, mg of an agent of the invention.

In addition, the pharmaceutical compositions of the present inventioncan be made up in a solid form (including without limitation capsules,tablets, pills, granules, powders or suppositories), or in a liquid form(including without limitation solutions, suspensions or emulsions). Thepharmaceutical compositions can be subjected to conventionalpharmaceutical operations such as sterilization and/or can containconventional inert diluents, lubricating agents, or buffering agents, aswell as adjuvants, such as preservatives, stabilizers, wetting agents,emulsifers and buffers, etc.

Typically, the pharmaceutical compositions are tablets or gelatincapsules comprising the active ingredient together with

-   -   a) diluents, e.g., lactose, dextrose, sucrose, mannitol,        sorbitol, cellulose and/or glycine;    -   b) lubricants, e.g., silica, talcum, stearic acid, its magnesium        or calcium salt and/or polyethyleneglycol; for tablets also    -   c) binders, e.g., magnesium aluminum silicate, starch paste,        gelatin, tragacanth, methylcellulose, sodium        carboxymethylcellulose and/or polyvinylpyrrolidone; if desired    -   d) disintegrants, e.g., starches, agar, alginic acid or its        sodium salt, or effervescent mixtures; and/or    -   e) absorbents, colorants, flavors and sweeteners.

Tablets may be either film coated or enteric coated according to methodsknown in the art.

Suitable compositions for oral administration include an effectiveamount of a compound of the invention in the form of tablets, lozenges,aqueous or oily suspensions, dispersible powders or granules, emulsion,hard or soft capsules, or syrups or elixirs. Compositions intended fororal use are prepared according to any method known in the art for themanufacture of pharmaceutical compositions and such compositions cancontain one or more agents selected from the group consisting ofsweetening agents, flavoring agents, coloring agents and preservingagents in order to provide pharmaceutically elegant and palatablepreparations. Tablets may contain the active ingredient in admixturewith nontoxic pharmaceutically acceptable excipients which are suitablefor the manufacture of tablets. These excipients are, for example, inertdiluents, such as calcium carbonate, sodium carbonate, lactose, calciumphosphate or sodium phosphate; granulating and disintegrating agents,for example, corn starch, or alginic acid; binding agents, for example,starch, gelatin or acacia; and lubricating agents, for example magnesiumstearate, stearic acid or talc. The tablets are uncoated or coated byknown techniques to delay disintegration and absorption in thegastrointestinal tract and thereby provide a sustained action over alonger period. For example, a time delay material such as glycerylmonostearate or glyceryl distearate can be employed. Formulations fororal use can be presented as hard gelatin capsules wherein the activeingredient is mixed with an inert solid diluent, for example, calciumcarbonate, calcium phosphate or kaolin, or as soft gelatin capsuleswherein the active ingredient is mixed with water or an oil medium, forexample, peanut oil, liquid paraffin or olive oil.

Certain injectable compositions are aqueous isotonic solutions orsuspensions, and suppositories are advantageously prepared from fattyemulsions or suspensions. Said compositions may be sterilized and/orcontain adjuvants, such as preserving, stabilizing, wetting oremulsifying agents, solution promoters, salts for regulating the osmoticpressure and/or buffers. In addition, they may also contain othertherapeutically valuable substances. Said compositions are preparedaccording to conventional mixing, granulating or coating methods,respectively, and contain about 0.1-75%, or contain about 1-50%, of theactive ingredient.

Suitable compositions for transdermal application include an effectiveamount of a compound of the invention with a suitable carrier. Carrierssuitable for transdermal delivery include absorbable pharmacologicallyacceptable solvents to assist passage through the skin of the host. Forexample, transdermal devices are in the form of a bandage comprising abacking member, a reservoir containing the compound optionally withcarriers, optionally a rate controlling barrier to deliver the compoundof the skin of the host at a controlled and predetermined rate over aprolonged period of time, and means to secure the device to the skin.

Suitable compositions for topical application, e.g., to the skin andeyes, include aqueous solutions, suspensions, ointments, creams, gels orsprayable formulations, e.g., for delivery by aerosol or the like. Suchtopical delivery systems will in particular be appropriate for dermalapplication, e.g., for the treatment of skin cancer, e.g., forprophylactic use in sun creams, lotions, sprays and the like. They arethus particularly suited for use in topical, including cosmetic,formulations well-known in the art. Such may contain solubilizers,stabilizers, tonicity enhancing agents, buffers and preservatives.

As used herein a topical application may also pertain to an inhalationor to an intranasal application. They may be conveniently delivered inthe form of a dry powder (either alone, as a mixture, for example a dryblend with lactose, or a mixed component particle, for example withphospholipids) from a dry powder inhaler or an aerosol spraypresentation from a pressurised container, pump, spray, atomizer ornebuliser, with or without the use of a suitable propellant.

The present invention further provides anhydrous pharmaceuticalcompositions and dosage forms comprising the compounds of the presentinvention as active ingredients, since water may facilitate thedegradation of certain compounds.

Anhydrous pharmaceutical compositions and dosage forms of the inventioncan be prepared using anhydrous or low moisture containing ingredientsand low moisture or low humidity conditions. An anhydrous pharmaceuticalcomposition may be prepared and stored such that its anhydrous nature ismaintained. Accordingly, anhydrous compositions are packaged usingmaterials known to prevent exposure to water such that they can beincluded in suitable formulary kits. Examples of suitable packaginginclude, but are not limited to, hermetically sealed foils, plastics,unit dose containers (e.g., vials), blister packs, and strip packs.

The invention further provides pharmaceutical compositions and dosageforms that comprise one or more agents that reduce the rate by which thecompound of the present invention as an active ingredient willdecompose. Such agents, which are referred to herein as “stabilizers,”include, but are not limited to, antioxidants such as ascorbic acid, pHbuffers, or salt buffers, etc.

In accordance with the foregoing, in a further aspect, the inventionrelates to an agent of the invention for use as a medicament, forexample for the treatment or prevention of a neurological or vascularcondition, disease or disorder, in which beta-amyloid generation oraggregation plays a role, or for the suppression of the metastasisprocess associated with tumor cells, or for the treatment or preventionof loss of β cell mass and/or function. In one embodiment, the inventionrelates to an agent of the invention for use in the treatment of adisease or disorder mediated by BACE-1, BACE-2 or cathepsin D activity.In another embodiment, the invention relates to an agent of theinvention for use in the treatment or prevention of Alzheimer's Diseaseor mild cognitive impairment. In a further embodiment, the inventionrelates to an agent of the invention for use in the treatment orprevention of insulin resistance, glucose intolerance, type 2 diabetes,obesity, hypertension, or diabetic complications. In yet anotherembodiment, the invention relates to a compound of the invention for usein the treatment of impaired glucose tolerance or Type 2 diabetes.

In a further aspect, the invention relates to the use of an agent of theinvention as an active pharmaceutical ingredient in a medicament, forexample for the treatment or prevention of a neurological or vascularcondition, disease or disorder, in which beta-amyloid generation oraggregation plays a role, or for the suppression of the metastasisprocess associated with tumor cells, or for the treatment or preventionof loss of β cell mass and/or function. In a further embodiment, theinvention relates to the use of an agent of the invention as an activepharmaceutical ingredient in a medicament for the treatment orprevention of a disease or disorder mediated by BACE-1, BACE-2 orcathepsin D activity. In one embodiment, the invention relates to theuse of an agent of the invention as an active pharmaceutical ingredientin a medicament for the treatment or prevention of Alzheimer's Diseaseor mild cognitive impairment. In a further embodiment, the inventionrelates to the use of a compound of the invention as an activepharmaceutical ingredient in a medicament for the treatment orprevention of insulin resistance, glucose intolerance, type 2 diabetes,obesity, hypertension, or diabetic complications. In yet a furtherembodiment, the invention relates to the use of a compound of theinvention as an active pharmaceutical ingredient in a medicament for thetreatment or prevention of impaired glucose tolerance or Type 2diabetes.

In a further aspect, the invention relates to the use of an agent of theinvention for the manufacture of a medicament for the treatment orprevention of a neurological or vascular condition, disease or disorder,in which beta-amyloid generation or aggregation plays a role, or for thesuppression of the metastasis process associated with tumor cells, orfor the treatment or prevention of loss of β cell mass and/or function.In a further embodiment, the invention relates to the use of an agent ofthe invention for the manufacture of a medicament for the treatment orprevention of a disease or disorder mediated by BACE-1, BACE-2 orcathepsin D activity. In one embodiment, the invention relates to theuse of an agent of the invention for the manufacture of a medicament forthe treatment or prevention of Alzheimer's Disease or mild cognitiveimpairment. In a further embodiment, the invention relates to the use ofa compound of the invention as an active pharmaceutical ingredient in amedicament for the treatment or prevention of insulin resistance,glucose intolerance, type 2 diabetes, obesity, hypertension, or diabeticcomplications. In yet a further embodiment, the invention relates to theuse of a compound of the invention as an active pharmaceuticalingredient in a medicament for the treatment or prevention of impairedglucose tolerance or Type 2 diabetes.

In a further aspect, the invention relates to a method for the treatmentor prevention of a neurological or vascular condition, disease ordisorder, in which beta-amyloid generation or aggregation plays a role,or for the suppression of the metastasis process associated with tumorcells, or for the treatment or prevention of loss of β cell mass and/orfunction, in a subject in need of such treatment, prevention orsuppression, which method comprises administering to such subject aneffective amount of an agent of the invention. In one embodiment, theinvention relates to a method of modulating BACE-1, BACE-2 or cathepsinD activity in a subject, wherein the method comprises administering tothe subject a therapeutically effective amount of an agent of theinvention. In another embodiment, the invention relates to a method forthe treatment or prevention of a disease mediated by BACE-1, BACE-2 orcathepsin D activity, in a subject in need of such treatment orprevention, which method comprises administering to such subject aneffective amount of an agent of the invention. In yet anotherembodiment, the invention relates to a method for the treatment orprevention of Alzheimer's Disease or mild cognitive impairment, in asubject in need of such treatment or prevention, which method comprisesadministering to such subject an effective amount of an agent of theinvention. In a further embodiment, the invention relates to a methodfor the treatment or prevention of insulin resistance, glucoseintolerance, type 2 diabetes, obesity, hypertension, or diabeticcomplications, in a subject in need of such treatment or prevention,which method comprises administering to such subject a therapeuticallyeffective amount of a compound of the invention. In yet a furtherembodiment, the invention relates to a method for the treatment orprevention of impaired glucose tolerance or Type 2 diabetes, in asubject in need of such treatment or prevention, which method comprisesadministering to such subject a therapeutically effective amount of acompound of the invention.

An agent of the invention can be administered as sole activepharmaceutical ingredient or as a combination with at least one otheractive pharmaceutical ingredient effective, e.g., in the treatment orprevention of a neurological or vascular condition, disease or disorder,in which beta-amyloid generation or aggregation plays a role, or in thesuppression of the metastasis process associated with tumor cells, or inthe treatment or prevention of loss of β cell mass and/or function. Sucha pharmaceutical combination may be in the form of a unit dosage form,which unit dosage form comprises a predetermined quantity of each of theat least two active components in association with at least onepharmaceutically acceptable carrier or diluent. Alternatively, thepharmaceutical combination may be in the form of a package comprisingthe at least two active components separately, e.g. a pack ordispenser-device adapted for the concomitant or separate administrationof the at least two active components, in which these active componentsare separately arranged. In a further aspect, the invention relates tosuch pharmaceutical combinations.

In a further aspect, the invention therefore relates to a combinationcomprising a therapeutically effective amount of an agent of theinvention and a second drug substance, for simultaneous or sequentialadministration.

In one embodiment, the invention provides a product comprising an agentof the invention and at least one other therapeutic agent as a combinedpreparation for simultaneous, separate or sequential use in therapy. Inone embodiment, the therapy is the treatment of a disease or conditionmediated by BACE-1, BACE-2 or cathepsin D activity, such as Alzheimer'sDisease, mild cognitive impairment, impaired glucose tolerance or type 2diabetes.

In one embodiment, the invention provides a pharmaceutical compositioncomprising an agent of the invention and another therapeutic agent(s).Optionally, the pharmaceutical composition may comprise apharmaceutically acceptable carrier, as described above.

In one embodiment, the invention provides a kit comprising two or moreseparate pharmaceutical compositions, at least one of which contains anagent of the invention. In one embodiment, the kit comprises means forseparately retaining said compositions, such as a container, dividedbottle, or divided foil packet. An example of such a kit is a blisterpack, as typically used for the packaging of tablets, capsules and thelike. The kit of the invention may be used for administering differentdosage forms, for example, oral and parenteral, for administering theseparate compositions at different dosage intervals, or for titratingthe separate compositions against one another. To assist compliance, thekit of the invention typically comprises directions for administration.

In the combination therapies of the invention, the agent of theinvention and the other therapeutic agent may be manufactured and/orformulated by the same or different manufacturers. Moreover, thecompound of the invention and the other therapeutic may be broughttogether into a combination therapy: (i) prior to release of thecombination product to physicians (e.g. in the case of a kit comprisingthe compound of the invention and the other therapeutic agent); (ii) bythe physician themselves (or under the guidance of the physician)shortly before administration; (iii) in the patient themselves, e.g.during sequential administration of the compound of the invention andthe other therapeutic agent. Accordingly, the invention provides anagent of the invention for use in the treatment of a disease orcondition mediated by BACE-1, BACE-2 or cathepsin D activity, such asAlzheimer's Disease, impaired glucose tolerance or type 2 diabetes,wherein the medicament is prepared for administration with anothertherapeutic agent. The invention also provides the use of anothertherapeutic agent for treating a disease or condition mediated byBACE-1, BACE-2 or cathepsin D activity, such as Alzheimer's Disease,impaired glucose tolerance or type 2 diabetes, wherein the medicament isadministered with an agent of the invention.

The invention also provides an agent of the invention for use in amethod of treating a disease or condition mediated by BACE-1, BACE-2 orcathepsin D activity, such as Alzheimer's Disease, impaired glucosetolerance or type 2 diabetes, wherein the agent of the invention isprepared for administration with another therapeutic agent. Theinvention also provides another therapeutic agent for use in a method oftreating a disease or condition mediated by BACE-1, BACE-2 or cathepsinD activity, such as Alzheimer's Disease, impaired glucose tolerance ortype 2 diabetes, wherein the other therapeutic agent is prepared foradministration with an agent of the invention. The invention alsoprovides an agent of the invention for use in a method of treating adisease or condition mediated by BACE-1, BACE-2 or cathepsin D activity,such as Alzheimer's Disease, impaired glucose tolerance or type 2diabetes, wherein the agent of the invention is administered withanother therapeutic agent. The invention also provides anothertherapeutic agent for use in a method of treating a disease or conditionmediated by BACE-1, BACE-2 or cathepsin D activity, such as Alzheimer'sDisease, impaired glucose tolerance or type 2 diabetes, wherein theother therapeutic agent is administered with an agent of the invention.

The invention also provides the use of an agent of the invention fortreating a disease or condition mediated by BACE-1, BACE-2 or cathepsinD activity, such as Alzheimer's Disease, impaired glucose tolerance ortype 2 diabetes, wherein the patient has previously (e.g. within 24hours) been treated with another therapeutic agent. The invention alsoprovides the use of another therapeutic agent for treating a disease orcondition mediated by BACE-1, BACE-2 or cathepsin D activity, such asAlzheimer's Disease, impaired glucose tolerance or type 2 diabetes,wherein the patient has previously (e.g. within 24 hours) been treatedwith an agent of the invention.

In one embodiment, the invention relates to a compound of the invention,or a pharmaceutically acceptable salt thereof, in combination withanother therapeutic agent wherein the other therapeutic agent isselected from:

(a) acetylcholinesterase inhibitors, such as donepezil (Aricept™),rivastigmine (Exelon™) and galantamine (Razadyne™);

(b) glutamate antagonists, such as memantine (Namenda™);

(c) antidepressant medications for low mood and irritability, such ascitalopram (Celexa™) fluoxetine (Prozac™), paroxeine (Paxil™),sertraline (Zoloft™) and trazodone (Desyrel™);

(d) anxiolytics for anxiety, restlessness, verbally disruptive behaviorand resistance, such as lorazepam (Ativan™) and oxazepam (Serax™);

(e) antipsychotic medications for hallucinations, delusions, aggression,agitation, hostility and uncooperativeness, such as aripiprazole(Abilify™), clozapine (Clozaril™), haloperidol (Haldol™), olanzapine(Zyprexa™), quetiapine (Seroquel™), risperidone (Risperdal™) andziprasidone (Geodon™);

(f) mood stabilizers, such as carbamazepine (Tegretol™) and divalproex(Depakote™);

(g) nicotinic apha—7 agonists;

(h) mGluR5 antagonists;

(i) H3 agonists; and

(j) amyloid therapy vaccines.

Thus, in one embodiment, the invention provides a pharmaceuticalcomposition comprising;

i) a compound of the invention, or a pharmaceutically acceptable saltthereof, and

ii) at least one compound selected from

-   -   a) acetylcholinesterase inhibitors,    -   b) glutamate antagonists,    -   c) antidepressant medications,    -   d) anxiolytics,    -   e) antipsychotic medications,    -   (f) mood stabilizers,    -   (g) nicotinic apha—7 agonists,    -   (h) mGluR5 antagonists,    -   (i) H3 agonists,    -   (j) amyloid therapy vaccines, and        ii) one or more pharmaceutically acceptable carriers.

In another embodiment, the invention relates to a compound of theinvention, or a pharmaceutically acceptable salt thereof, in combinationwith another therapeutic agent wherein the other therapeutic agent isselected from:

a) antidiabetic agents, such as insulin, insulin derivatives andmimetics; insulin secretagogues such as the sulfonylureas, e.g.,Glipizide, glyburide and Amaryl; insulinotropic sulfonylurea receptorligands such as meglitinides, e.g., nateglinide and repaglinide; proteintyrosine phosphatase-1B (PTP-1B) inhibitors such as PTP-112; GSK3(glycogen synthase kinase-3) inhibitors such as SB-517955, SB-4195052,SB-216763, NN-57-05441 and NN-57-05445; RXR ligands such as GW-0791 andAGN-194204; sodium-dependent glucose cotransporter inhibitors such asT-1095; glycogen phosphorylase A inhibitors such as BAY R3401;biguanides such as metformin; alpha-glucosidase inhibitors such asacarbose; GLP-1 (glucagon like peptide-1), GLP-1 analogs such asExendin-4 and GLP-1 mimetics; and DPPIV (dipeptidyl peptidase IV)inhibitors such as vildagliptin;

b) hypolipidemic agents such as 3-hydroxy-3-methyl-glutaryl coenzyme A(HMG-CoA) reductase inhibitors, e.g., lovastatin, pitavastatin,simvastatin, pravastatin, cerivastatin, mevastatin, velostatin,fluvastatin, dalvastatin, atorvastatin, rosuvastatin and rivastatin;squalene synthase inhibitors; FXR (farnesoid X receptor) and LXR (liverX receptor) ligands; cholestyramine; fibrates; nicotinic acid bile acidbinding resins such as cholestyramine; fibrates; nicotinic acid andother GPR109 agonists; cholesterol absorption inhibitors such asezetimibe; CETP inhibitors (cholesterol-ester-transfer-proteininhibitors), and aspirin;

c) anti-obesity agents such as orlistat, sibutramine and CannabinoidReceptor 1 (CB1) antagonists e.g. rimonabant; and

d) anti-hypertensive agents, e.g., loop diuretics such as ethacrynicacid, furosemide and torsemide; angiotensin converting enzyme (ACE)inhibitors such as benazepril, captopril, enalapril, fosinopril,lisinopril, moexipril, perinodopril, quinapril, ramipril andtrandolapril; inhibitors of the Na-K-ATPase membrane pump such asdigoxin; neutralendopeptidase (NEP) inhibitors; ACE/NEP inhibitors suchas omapatrilat, sampatrilat and fasidotril; angiotensin II antagonistssuch as candesartan, eprosartan, irbesartan, losartan, telmisartan andvalsartan, in particular valsartan; renin inhibitors such as ditekiren,zankiren, terlakiren, aliskiren, RO 66-1132 and RO-66-1168; β-adrenergicreceptor blockers such as acebutolol, atenolol, betaxolol, bisoprolol,metoprolol, nadolol, propranolol, sotalol and timolol; inotropic agentssuch as digoxin, dobutamine and milrinone; calcium channel blockers suchas amlodipine, bepridil, diltiazem, felodipine, nicardipine, nimodipine,nifedipine, nisoldipine and verapamil; aldosterone receptor antagonists;and aldosterone synthase inhibitors.

e) agonists of peroxisome proliferator-activator receptors, such asfenofibrate, pioglitazone, rosiglitazone, tesaglitazar, BMS-298585,L-796449, the compounds specifically described in the patent applicationWO 2004/103995 i.e. compounds of examples 1 to 35 or compoundsspecifically listed in claim 21, or the compounds specifically describedin the patent application WO 03/043985 i.e. compounds of examples 1 to 7or compounds specifically listed in claim 19 and especially(R)-1-{4-[5-methyl-2-(4-trifluoromethyl-phenyl)-oxazol-4-ylmethoxy]-benzenesulfonyl}-2,3-dihydro-1H-indole-2-carboxylicor a salt thereof.

Thus, in one embodiment, the invention provides a pharmaceuticalcomposition comprising;

i) a compound of the invention, or a pharmaceutically acceptable saltthereof, and

ii) at least one compound selected from

-   -   a) antidiabetic agents,    -   b) hypolipidemic agents,    -   c) anti-obesity agents,    -   d) anti-hypertensive agents,    -   e) agonists of peroxisome proliferator-activator receptors, and

ii) one or more pharmaceutically acceptable carriers.

Other specific anti-diabetic compounds are described by Patel Mona inExpert Opin Investig Drugs, 2003, 12(4), 623-633, in the FIGS. 1 to 7.

The structure of the therapeutic agents identified by code numbers,generic or trade names may be taken from the actual edition of thestandard compendium “The Merck Index” or from databases, e.g., PatentsInternational (e.g. IMS World Publications).

EXAMPLES NMR Methods

Proton spectra are recorded on a Bruker 400 MHz ultrashield spectrometerunless otherwise noted. Chemical shifts are reported in ppm relative tomethanol (δ 3.31), dimethyl sulfoxide (δ 2.50), or chloroform (δ 7.29).A small amount of the dry sample (1-5 mg) is dissolved in an appropriatedeuterated solvent (0.7 mL). The shimming is automated and the spectraobtained in accordance with normal procedure.

General Chromatography Conditions UPLC Method H1 (Rt_(H1)):

-   HPLC-column dimensions: 2.1×50 mm-   HPLC-column type: Acquity UPLC HSS T3, 1.8 μm-   HPLC-eluent: A) water+0.05 Vol.-% formic acid+3.75 mM ammonium    acetate B) ACN+0.04 Vol.-% formic acid-   HPLC-gradient: 2-98% B in 1.4 min, 98% B 0.75 min, flow=1.2 ml/min-   HPLC-column temperature: 50° C.

UPLC Method H2 (Rt_(H2)):

-   HPLC-column dimensions: 2.1×50 mm-   HPLC-column type: Acquity UPLC HSS T3, 1.8 μm-   HPLC-eluent: A) water+0.05 Vol.-% formic acid+3.75 mM ammonium    acetate B) ACN+0.04 Vol.-% formic acid-   HPLC-gradient: 5-98% B in 1.4 min, 98% B 0.4 min, flow=1.0 ml/min-   HPLC-column temperature: 60° C.

LCMS Method H3 (Rt_(H3)):

-   HPLC-column dimensions: 4.0×20 mm-   HPLC-column type: Mercury MS Synergi, 2 μm-   HPLC-eluent: A) water+0.1 Vol.-% formic acid, B) ACN-   HPLC-gradient: 0.5 min 70% B, 70-100% B in 1 min, 0.9 min 100% B,    flow=2.0 ml/min-   HPLC-column temperature: 30° C.

LCMS Method H4 (Rt_(H4)):

-   HPLC-column dimensions: 2.1×30 mm-   HPLC-column type: Ascentis Express C18, 2.8 μm-   HPLC-eluent A) water+0.05 Vol.-% formic acid+3.75 mM ammonium    acetate B) ACN+0.04 Vol.-% formic acid-   HPLC-gradient: 2-98% B in 1.4 min, 0.75 min 98% B, flow=1.2 ml/min-   HPLC-column temperature: 50° C.

HPLC Method H5 (Rt_(H5)):

-   HPLC-column dimensions: 3.0×30 mm-   HPLC-column type: Zorbax SB-C18, 1.8 μm-   HPLC-eluent: A) water+0.05 Vol.-% TFA; B) ACN+0.05 Vol.-% TFA-   HPLC-gradient: 0-100% B in 3.25 min, 0.75 min 100% B, flow=0.7    ml/min-   HPLC-column temperature: 35° C.

UPLC Method H6 (Rt_(H6)):

-   HPLC-column dimensions: 2.1×50 mm-   HPLC-column type: Acquity UPLC HSS T3, 1.8 μm-   HPLC-eluent: A) water+0.1 Vol.-% TFA; B) ACN+0.1 Vol.-% TFA-   HPLC-gradient: 10-95% B in 1.5 min, flow=1.0 ml/min

HPLC Method H7 (Rt_(H7)):

-   HPLC-column dimensions: 3.0×30 mm-   HPLC-column type: Zorbax SB-C18, 1.8 μm-   HPLC-eluent: A) water+0.05 Vol.-% TFA; B) ACN+0.05 Vol.-% TFA-   HPLC-gradient: 30-100% B in 3.25 min, 0.75 min 100% B, flow=0.7    ml/min-   HPLC-column temperature: 35° C.

HPLC Method H8 (Rt_(H8)):

-   HPLC-column dimensions: 3.0×30 mm-   HPLC-column type: Zorbax SB-C18, 1.8 μm-   HPLC-eluent: A) water+0.05 Vol.-% TFA; B) ACN+0.05 Vol.-% TFA-   HPLC-gradient: 10-100% B in 3.25 min, 0.75 min 100% B, flow=0.7    ml/min-   HPLC-column temperature: 35° C.

Abbreviations

ACN acetonitrileAcOH acetic acidaq. aqueousBoc₂O tert-butyl dicarbonateBuLi butyl lithiumCSA campher sulfonic acidDAST diethylaminosulfur trifluoridedba dibenzylideneacetoneDCM dichloromethaneDEAD diethyl azodicarboxylateDIAD diisopropyl azodicarboxylateDIPEA diisopropylethylamineDMA dimethylacetamideDMF dimethylformamideDMSO dimethylsulfoxideDMTr 4,4′-dimethoxytritylDPPF 1,1′-bis-diphenylphosphino-ferroceneEDC 1-(3-dimethylaminopropyl)-3-ethylcarbodiimideEt₃N triethylamineEtOAc ethyl acetateEtOH ethanolh hour(s)hex hexaneHOAt 1-hydroxy-7-aza-benztriazoleHPLC high performance liquid chromatographyLCMS liquid chromatography with mass spectrometryLDA lithium diisopropylamidemCPBA 3-chloroperbenzoic acidMeOH methanolmin minute(s)MS mass spectrometryNEt₃ triethylamineNMR nuclear magnetic resonance spectrometryR_(f) retention factor (TLC)RP reverse phaseRt retention timert room temperaturesat. saturatedTBME tert-butyl-methyl-etherTFA trifluoroacetic acidTHF tetrahydrofuranTLC thin layer chromatographyXantphos 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene

Example 1 5-Cyano-3-methyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

a) 2-Bromo-5-fluoro-4-triethylsilanylpyridine

To a solution of diisopropylamine (25.3 g, 250 mmol) in THF (400 ml) wasadded n-BuLi (100 ml, 2.5 mol/L in hexanes) below −50° C. A solution of2-bromo-5-fluoropyridine (41.9 g, 238 mmol) in THF (60 ml) was added tothe LDA-solution at −78° C. in a dropwise manner below −63° C. After 60minutes at −78° C. triethylchlorosilane (44 ml, 262 mmol) was added in afast manner keeping the temperature below −50° C. The cooling bath wasremoved and the reaction mixture was allowed to reach −20° C. Thereaction mixture was poured on a mixture of 1M aq. HCl (250 ml) and aq.NH₄Cl (10%). Tert.-butyl methyl ether was added and the layers wereseparated. The organic phase was washed with brine, dried over magnesiumsulfate, filtered and evaporated to give a yellow liquid. Distillation(bp. 99-101° C., 0.5 mmHg). afforded the title compound as a slightlyyellow liquid: 66.26 g (96% yield).

¹H-NMR (400 MHz, CDCl₃): δ 8.17 (s, 1H), 7.42 (d, 1H), 1.01-0.97 (m,9H), 0.92-0.87 (m, 6H).

b) 1-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-ethanone

To a solution of diisopropylamine (25.4 g, 251 mmol) in THF (500 ml) wasadded n-BuLi (100 ml, 2.5 mol/L in hexanes) below −50° C. A solution of2-bromo-5-fluoro-4-triethylsilanyl-pyridine (56.04 g, 193 mmol) in THF(60 ml) was added to the LDA-solution at −78° C. in a dropwise mannerbelow −65° C. After 70 minutes at −78° C. DMA (23.51 ml, 251 mmol) wasadded dropwise in a fast manner to the deep red solution keeping thetemperature below −57° C. After 15 minutes the cooling bath was removedand the reaction mixture was allowed to reach −40° C. The cold reactionmixture was poured on a mixture of 2M aq. HCl (250 ml)/water (200ml)/brine (100 ml). Tert.-butyl methyl ether was added and the layerswere separated. The organic phase was washed twice with brine, driedover magnesium sulfate, filtered and evaporated to give a yellow oil.The crude product (64.76 g) was chromatographed over silica gel(hexane/TBME) to give the title compound as a yellow liquid: 58.3 g (91%yield).

TLC (hexane/TBME 99:1): R_(f)=0.25;

¹H-NMR (400 MHz, CDCl₃): δ 7.55 (d, 1H), 2.67 (3, 3H), 0.98-0.93 (m,9H), 0.91-0.85 (m, 6H).

c) (R)-2-Methyl-propane-2-sulfinicacid[1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-eth-(E)-ylidene]-amide

A mixture of titantetraethoxide (4.26 g, 18.69 mmol),(R)-tert.-butylsulfinamide (1.246 g, 10.28 mmol) and1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-ethanone (3.45 g,9.34 mmol, 90% pure) in THF (25 ml) was refluxed under a nitrogenatmosphere for 6 hours. The cold reaction mixture was poured ontoicecold brine (200 ml) with gentle stirring. The precipitate wasfiltered through a pad of hyflo and and washed with ethyl acetate. Thefiltrate was diluted with ethyl acetate and washed with brine, driedover sodium sulfate, filtered and evaporated. The crude yellow oil (4.55g) was chromatographed over silica gel (cyclohexane/ethyl acetate 94:6)to give the title compound as a yellow oil. 3.35 g (82% yield).

TLC (cyclohexane/ethyl acetate 5:1): R_(f)=0.50;

HPLC: Rt_(H1)=1.56 min; ESIMS: 435, 437 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, CDCl₃): δ 7.48 (d, 1H), 2.28 (s, 3H), 1.34 (s, 9H),1.01-0.98 (m, 9H), 0.92-0.89 (m, 6H).

d)(R)-3-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester

To a suspension of zinc (466 mg, 7.12 mmol) and copper(I) chloride (34mg, 0.344 mmol) in dry THF (20 ml) were added 3 drops oftrimethylchlorosilane under nitrogen to activate the zinc. After 10minutes ethyl 2-bromo-2,2-difluoroacetate (1.398 g, 6.89 mmol) was addedslowly by syringe over a period of 10 minutes at 25° C. (slightlyexothermic). The reaction mixture was kept in an ultrasound bath for 45minutes. This black fine suspension was added dropwise to a solution of(R)-2-methyl-propane-2-sulfinic acid[1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-eth-(E)-ylidene]-amide)(1 g, 2.296 mmol) in dry THF (10 ml) at rt under inert atmosphere. After4 h at rt the reaction mixture was added to a cold aq. ammonium chloridesolution (5%) and was diluted with ethyl acetate. The organic phase waswashed with aq. citric acid (5% solution), water, sat. sodiumbicarbonate solution and brine, dried over sodium sulfate, filtered andconcentrated. The crude brownish oil (1.5 g) was chromatographed oversilica gel (cyclohexane/ethyl acetate 83:17) to give the title compoundas a light yellow oil. 984 mg (77% yield).

TLC (cyclohexane/ethyl acetate 2:1): R_(f)=0.46;

HPLC: Rt_(H1)=1.54 min; ESIMS: 559, 561 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, CDCl₃): δ 7.40 (d, 1H), 5.48 (s, NH), 4.38 (q, 2H),2.07 (s, 3H), 1.26 (s, 9H), 1.00-0.96 (m, 9H), 0.90-0.86 (m, 6H).

Minor diastereoisomer R_(f)=0.64 (2:1 cyclohexane:ethyl acetate).

e)(R)-3-(6-Bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester

Freshly ground KF (195 mg, 3.36 mmol) was added to a solution of(R)-3-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester (940 mg, 1.68 mmol) and acetic acid (0.192 ml, 3.36mmol) in THF (7 ml). DMF (7 ml) was added and the suspension was stirredat rt. After 2 h the reaction mixture was diluted with ethyl acetate andwashed with sat. sodium bicarbonate solution and brine, dried oversodium sulfate, filtered and evaporated. The crude product (733 mg) waschromatographed over silica gel (cyclohexane/ethyl acetate 7:3) to givethe title compound as a slightly yellow oil. 664 mg (88% yield).

TLC (cyclohexane/ethyl acetate 1:1): R_(f)=0.38;

HPLC: Rt_(H1)=1.08 min; ESIMS: 445, 447 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, CDCl₃): δ 7.51-7.46 (dd, 1H), 7.35 (t, 1H), 5.38 (br.s, 1H, NH), 4.37 (q, 2H), 2.07 (s, 3H), 1.39 (t, 3H), 1.26 (s, 9H).

f) (R)-2-Methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1-methyl-propyl]amide

To a solution of(R)-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester (513 mg, 1.15 mmol) in THF (11.5 ml) was addedlithiumborohydride (52.8 mg, 2.30 mmol). The slightly exothermicreaction was stirred for 2.5 h at room temperature. Crushed ice wasadded and the reaction mixture was diluted with ethyl acetate. Theorganic phase was washed with water and brine, dried over sodiumsulfate, filtered and evaporated; 465 mg (quantitative yield) slightlyyellow resin which was used without purification in the next step.

TLC (toluene/ethyl acetate 7:3): R_(f)=0.16;

HPLC: Rt_(H1)=0.93 min; ESIMS: 403, 405 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, CDCl₃): δ 7.52 (dd, 1H), 7.38 (dd, 1H), 5.84 (s broad,1H), 4.32 (dd, 1H), 4.02 (m, 1H), 3.81 (m, 1H), 2.05 (s, 3H), 1.31 (s,9H).

g) (R)-3-Amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol

To a solution of (R)-2-methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1-methyl-propyl]amide(1.33 g, 3.30 mmol) in dioxane (26.6 ml) was added HCl/dioxane 4N (3.3ml, 13.19 mmol). The reaction mixture was stirred for 21 hours at roomtemperature. The solvent was evaporated and to the residue was addedethyl acetate and crushed ice. The organic phase was extracted withwater and was made alkaline with solid potassium carbonate. The aqueousphase was extracted with ethyl acetate, dried over sodium sulfate,filtered and evaporated. 930 mg colourless solid (94% yield).

TLC (toluene/ethyl acetate 7:3): R_(f)=0.25;

HPLC: Rt_(H1)=0.44 min; ESIMS: 299, 301 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, DMSO-D₆): δ 7.73 (m, 2H, Ar), 7.29 (broad s, 1H), 6.69(broad s, 1H), 5.30 (t, 1H), 3.79 (m, 2H), 1.57 (d, 3H).

h)(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazine-2-ylamine

A solution of(R)-3-amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol(150 mg, 0.49 mmol) and bromocyan (106 mg, 1 mmol) in ethanol (5 ml) washeated for 19 h at 85° C. in a capped microwave vial. The solvent wasevaporated and the residue was dissolved in ethyl acetate. The organicphase was washed with aq. ammonia, water and brine, dried over sodiumsulfate, filtered and evaporated. The crude product (136 mg) waschromatographed over silica (toluene/ethyl acetate 1:1) to affordrecovered starting material (27 mg) and the title compound: 64 mg (40%yield).

TLC (toluene/ethyl acetate 1:1): R_(f)=0.17;

HPLC: Rt_(H1)=0.56 min; ESIMS: 324, 326 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, DMSO-D₆): δ 7.69 (m, 2H), 5.82 (broad s, 2H), 4.36 (m,1H), 4.17 (m, 1H), 1.63 (s, 3H).

i)[(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazine-2-yl]-carbamicacid tert-butyl ester

A solution of(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazine-2-ylamine(60 mg, 0.185 mmol), Boc-anhydride (42.3 mg, 0.194 mmol) and Hünig'sbase (64.7 μl, 0.37 mmol) in dichloromethane (1.9 ml) was stirred at rtfor 3 days. The reaction mixture was diluted with ethyl acetate, washedwith as. Bicarbonate solution, water and brine, dried over sodiumsulfate, filtered and evaporated. 76 mg (85% yield).

TLC (toluene/ethyl acetate 7:3): R_(f)=0.38;

HPLC: Rt_(H1)=1.08 min; ESIMS: 424, 426 [(M+H)⁺, 1Br];

¹H-NMR (400 MHz, CDCl₃): δ 7.58-7.30 (m, 2H, Ar), 4.40-4.30 (m, 2H),1.90 (broad s, 3H), 1.52 (s, 9H).

j)((R)-4-{6-[(5-Cyano-3-methyl-pyridine-2-carbonyl)-amino]-3-fluoro-pyridin-2-yl}-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-carbamicacid tert-butyl ester

A degassed mixture of[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazine-2-yl]-carbamicacid tert-butyl ester (70 mg, 0.145 mmol),5-cyano-3-methyl-pyridine-2-carboxylic acid amide (25.7 mg, 0.160 mmol),Xantphos (30.2 mg, 0.052 mmol), caesium carbonate (67.6 mg, 0.203 mmol)and Pd₂(dba)₃ (16.45 mg, 0.017 mmol) was heated under argon in dioxane(2.9 ml) at 60° C. for 5 hours. The reaction mixture (grey-brownsuspension) was diluted with ethyl acetate and aq. bicarbonate solutionand was then filtered. The filtrate was washed with water and brine,dried over sodium sulfate, filtered and evaporated. 166 mg brown solid.The crude product was chromatographed over silica gel (toluene/ethylacetate 7:3) to give the title compound as a white solid. 28 mg (38%yield).

TLC (toluene/ethyl acetate 7:3): R_(f)=0.25;

HPLC: Rt_(H1)=1.18 min; ESIMS: 505 [(M+H)⁺];

1H-NMR (400 MHz, CDCl₃): δ 10.7 (broad s, 1H), 10.49 (broad s, 1H), 8.77(d, 1H), 8.49 (broad d, 1H), 7.99 (d, 1H), 7.6 (broad t, 1H), 4.49-4.30(m, 2H), 2.88 (s, 3H), 1.92 (broad s, 3H), 1.55 (s, 9H).

k) 5-Cyano-3-methyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

A solution of((R)-4-{6-[(5-cyano-3-methyl-pyridine-2-carbonyl)-amino]-3-fluoro-pyridin-2-yl}-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-carbamicacid tert-butyl ester (26 mg, 0.052 mmol) and TFA (200 μl, 2.6 mmol) indichloromethane (1.3 ml) was stirred at rt for 5 hours. The reactionmixture was evaporated and the residue diluted with aq. ammonia andethyl acetate, washed with water and brine, dried over sodium sulfate,filtered and evaporated. 24 mg yellowish solid. Trituration withcyclohexane afforded the title compound as a slightly yellow solid. 17mg (80% yield).

HPLC: Rt_(H1)=0.72 min; ESIMS: 405 [(M+H)⁺];

¹H-NMR (400 MHz, DMSO-D₆): δ 10.71 (broad s, 1H, NH), 9.01 (broad s,1H), 8.43 (broad s, 1H), 8.19 (broad d, 1H), 7.76 (t, 1H), 5.77 (broads, 2H, NH₂), 4.32 (m, 2H), 2.61 (s, 3H), 1.67 (broad s, 3H).

Example 2

The compound listed in Table 1 was prepared by a procedure analogous tothat used in Example 1.

TABLE 2 MS [m/z; Example Compound ¹H-NMR (δ; CDCl₃) (M + 1)⁺] 2

10.15 (br · s, 1H), 8.85 (d, 1H), 8.39 (dd, 1H), 8.21 (d, 1H), 7.53 (dd,1H), 4.22-4.14 (m, 2H), 1.84 (t, 3H) LCMS: Rt_(H1) = 0.67 min. [M + 1] =425.0, 427.0 3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4- methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

Example 3 3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

a) (R)-2-Methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1,3-dimethyl-butyl]-amide

To methylmagnesium chloride 3M in THF (38.3 ml, 115 mmol) was added asolution of(R)-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester (5.12 g, 11.5 mmol, example 1e)) in THF (102 ml) at rt.After 2 hr stirring the reaction was quenched with addition of anaqueous ammonium chloride solution. The mixture was diluted with ethylacetate and washed with water and brine, dried over sodium sulfate,filtered and evaporated. The crude product (4.78 g) was chromatographedover silica gel (cyclohexane/ethyl acetate 6:4) to give the titlecompound as a colourless solid. 2.97 g (59.9% yield).

TLC (cyclohexane/ethyl acetate 6:4, silica gel, UV 254): R_(f)=0.32;

LC-MS: Rt_(H1)=1.09 min; (100% pure; ESI+−MS: m/z 431 [(M+H)⁺]);

¹H-NMR (400 MHz, DMSO-d₆) δ=7.83-7.70 (m, 2H), 6.10 (s, 1H), 5.48 (s,1H), 1.93 (s, 3H), 1.23 (s, 3H), 1.18 (s, 9H), 1.07 (s, 3H).

b)(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine

A solution of (R)-2-methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1,3-dimethyl-butyl]-amide(2.95 g, 6.84 mmol) and cyanogen bromide (2.24 g, 20.52 mmol) in dryethanol (68 ml) was sealed with a glass stopper and heated at 85° C. for9 hr. The reaction solution was evaporated in vacuo and the crudeproduct was taken up with ethyl acetate and 2M aq. ammonia. The organicphase was washed with water and brine, dried over sodium sulfate,filtered and evaporated. The crude product (2.74 g) was chromatographedover silica gel (toluene/ethyl acetate 6:4) to give the title compoundas a colourless solid. 1.19 g (48.9% yield).

LC-MS: Rt_(H1)=67 min; (99% pure; ESI+−MS: m/z 352 [(M+H)⁺], 354);

¹H-NMR (400 MHz, DMSO-d₆) δ=7.72-7.59 (m, 2H), 5.83 (br. s, 2H), 1.67(d, J=4.0 Hz, 3H), 1.48 (s, 3H), 1.27 (d, J=2.0 Hz, 3H).

c)[Bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-amine

To a solution of(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine(106 mg, 0.301 mmol) and triethylamine (60.9 mg, 0.602 mmol) indichloromethane (3 ml) was added solid 4,4′-dimethoxytrityl chloride(112 mg, 0.331 mmol) under argon atmosphere. The green solution wasstirred at rt for 2 hrs and was then evaporated in vacuo. The crudeproduct was taken up with ethyl acetate and washed with aqueous sodiumbicarbonate solution, water and brine. The organic phase was dried oversodium sulfate, filtered and evaporated. Filtration over silica gel (4.4g, toluene/ethyl acetate 6:4) afforded the title compound as a blue-grayfoam (202 mg, 96%).

TLC (toluene/ethyl acetate 6:4, silica gel, UV 254): R_(f)=0.60;

LC-MS: Rt_(H1)=1.22 min; (94% pure; ESI+−MS: m/z 654 [(M+H)⁺]; 656);

¹H-NMR (400 MHz, DMSO-d₆) δ=7.72-7.61 (m, 2H), 7.32-7.13 (m, 9H),6.84-6.77 (m, 4H), 6.71 (br. s, 1H), 3.71 (s, 6H), 1.16 (br. s, 3H),1.12 (br. s, 3H), 1.07 (br. s, 3H).

d) 3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-{[bis-(4-methoxy-phenyl)-phenyl-methyl]-amino}-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

A degassed mixture of[bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-amine(196 mg, 0.299 mmol), 5-cyano-3-methyl-pyridine-2-carboxylic acid amide(59.8 mg, 0.329 mmol), Xantphos (62.4 mg, 0.108 mmol), caesium carbonate(139 mg, 0.419 mmol) and Pd₂(dba)₃ (33.9 mg, 0.036 mmol) was heatedunder argon in dioxane (6 ml) at 60° C. for 20 hours. The reactionmixture was diluted with ethyl acetate and aq. bicarbonate solution andwas then filtered through hyflo. The filtrate was washed with water andbrine, dried over sodium sulfate, filtered and evaporated to give 226 mgyellowish foam. The crude product was chromatographed over silica gel(toluene/ethyl acetate 8:2) to give the title compound as a light yellowfoam. 92 mg (38.6% yield).

LC-MS: Rt_(H1)=1.20 min (95% pure; ESI+−MS: 755, [(M+H)⁺]; 756, 757,758);

¹H-NMR (400 MHz, CDCl3): δ 10.24 (br. s, 1 NH), 8.74 (br. d, 1H), 8.36(dd, 1H), 8.21 (d, J=1.8 Hz, 1H), 7.50 (dd, 1H), 7.42-6.79 (m, 13H+1NH),3.79 (s, 6H), 1.60 (br. s, 3H), 0.89 (br. s, 3H), 0.78 (br. s, 3H).

e) 3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

A solution of 3-chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-{[bis-(4-methoxy-phenyl)-phenyl-methyl]-amino}-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide(85 mg, 0.113 mmol), TFA (572 μl, 7.43 mmol) and triethylsilane (54 μl,0.338 mmol) in dichloromethane (1.1 ml) was stirred at rt for 24 hours.The reaction mixture was evaporated and the residue diluted with ethylacetate, washed with water and brine, dried over sodium sulfate,filtered and evaporated to give 119 mg brown-yellowish resin. Theproduct was chromatographed over silica gel (RediSep 12 g, conditionedwith ethyl acetate/methanol 95:5 and eluted with ethyl acetate) to givethe title compound as a light yellow solid. 38 mg (74.6% yield).

TLC (ethyl acetate/methanol 95:5, silica gel, UV 254): R_(f)=0.29;

LC-MS: Rt_(H1)=0.76 min (100% pure; ESI+−MS: 453, [(M+H)⁺], 455);

¹H-NMR (400 MHz, CDCl3): δ 12.66 (very br. s, 1 NH), 12.03 (br. s, 1NH), 10.29 (br. s, 1 NH), 8.87 (d, J=1.8 Hz, 1H), 8.49 (dd, 1H), 8.18(d, J=1.8 Hz, 1H), 7.62 (dd, 1H), 5.74 (br. s, 1 NH), 2.01 (d, J=2.3 Hz,3H), 1.74 (s, 3H), 1.44 (d, J=2.3 Hz, 3H).

Example 4 5-Cyano-3-methyl-pyridine-2-carboxylic acid{6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide

a)1-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-3-methoxy-propan-1-one

To a solution of1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-ethanone (11.6 g,33.9 mmol, example 1, step b) in dichloromethane (50 ml) was addedHünigs-base (6.21 ml, 35.6 mmol) at 0° C. followed by TMS-triflate (6.43ml, 35.52 mmol, 1.05 eq.) under nitrogen. The reaction mixture wasstirred at 0° C. for 40 minutes. Dimethoxymethane (2.71 g, 35.6 mmol)and 2,6-di-tert-butylpyridine (0.648 g, 3.39 mmol) was added drop wiseat 0° C. TMS-triflate (0.61 ml, 3.39 mmol) was then added to thereaction mixture. After 30 min the cooling bath was removed and stirringwas continued at rt over night (18 h). The reaction mixture was pouredonto cold brine, diluted with ethyl acetate and the organic phase waswashed thoroughly with 10% NaHSO₄ solution, sat. sodium bicarbonatesolution (saturated with NaCl) and brine, dried over sodium sulfate,filtered and evaporated. The crude product (13.52 g) was chromatographedover silica gel (320 g, cyclohexane/ethyl acetate 95:5) to give thetitle compound as a yellow liquid: 9.18 g (72% yield).

TLC (cyclohexane/ethyl acetate 5:1): R_(f)=0.61;

LC-MS: Rt_(H1)=1.43 min (100% pure; ESI+−MS: 376, [(M+H)⁺], 378);

¹H-NMR (400 MHz, CDCl₃): δ 7.58 (d, J=2.9 Hz, 1H), 3.83 (t, J=6.2 Hz,2H), 3.41 (t, J=6.2 Hz, 2H), 3.39 (s, 3H), 1.06-0.82 (m, 15H).

b) (S)-2-Methyl-propane-2-sulfinic acid[1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-3-methoxy-prop-(E)-ylidene]-amide

A mixture of titantetraethoxide (11.03 g, 48.4 mmol),(S)-tert.-butylsulfinamide (3.52 g, 29 mmol) and1-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-3-methoxy-propan-1-one(9.1 g, 24.18 mmol) in THF (100 ml) was stirred at 60° C. under anitrogen atmosphere for 34 hours. The cold reaction mixture was dilutedwith ethyl acetate and poured onto icecold brine (200 ml) with gentlestirring. The precipitate was filtered through a pad of hyflo and andwashed with ethyl acetate. The filtrate was diluted with ethyl acetateand washed with brine, dried over sodium sulfate, filtered andevaporated. The crude yellowish-brown oil (10.67 g) was chromatographedover silica gel (Redisep column 120 g, cyclohexane/ethyl acetate 95:5)to give the title compound as a yellow-orange oil. 7.51 g (63.5% yield).

TLC (cyclohexane/ethyl acetate 10:1): R_(f)=0.23;

LC-MS: Rt_(H1)=1.53 min (98%, ESI+−MS: m/z 479 [(M+H)⁺, 1Br], 481).

c)(R)-3-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-5-methoxy-3-((S)-2-methyl-propane-2-sulfinylamino)-pentanoicacid ethyl ester

To a suspension of zinc (3.07 g, 47 mmol) and copper(I) chloride (233mg, 2.349 mmol) in dry THF (90 ml) were added 4 drops oftrimethylchlorosilane under nitrogen to activate the zinc. After 10minutes ethyl 2-bromo-2,2-difluoroacetate (9.54 g, 47 mmol) was addedslowly by syringe over a period of 20 minutes between 25° and 30° C.adjusted with an external cooling bath (exothermic). The reactionmixture was kept in an ultrasound bath for 30 minutes. This black finesuspension was added drop wise to a solution of(S)-2-methyl-propane-2-sulfinic acid[1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-3-methoxy-prop-(E)-ylidene]-amide(7.51 g, 15.66 mmol) in dry THF (75 ml) at 0° C. under inert atmosphere.After 15 min the reaction mixture was kept at 50° C. for 2 h and wasthen added to a cold aq. ammonium chloride solution (5%). Ethyl acetatewas added and the organic phase was washed with aq. citric acid (5%solution), water, sat. sodium bicarbonate solution and brine, dried oversodium sulfate, filtered and concentrated. The crude yellowish oil (9.77g, roughly a 4:1 mixture of diastereoisomers) was chromatographed oversilica gel (Redisep column 120 g, cyclohexane/ethyl acetate 85:15) togive the title compound as a yellow oil. 6.11 g yellow oil. (64.6%yield).

TLC (cyclohexane/ethyl acetate 2:1): R_(f)=0.47;

LC-MS: Rt_(H1)=1.54 min (100%, ESI+−MS: m/z 604 [(M+H)⁺, 1Br], 606);

¹H-NMR (400 MHz, CDCl₃): δ 7.45 (d, J=2.5 Hz, 1H), 6.63 (br. s, 1H),4.22-4.04 (m, 2H), 3.77-3.68 (m, 1H), 3.31-3.20 (m, 1H), 3.15 (s, 3H),3.11-3.00 (m, 1H), 2.97-2.84 (m, 1H), 1.35 (s, 9H), 1.15 (t, J=7.2 Hz,3H), 1.04-0.95 (m, 9H), 0.94-0.83 (m, 6H).

The minor diastereoisomer R_(f)=0.35 (2:1 cyclohexane:ethyl acetate wasnot isolated.

d)(R)-3-(6-Bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-5-methoxy-3-((S)-2-methyl-propane-2-sulfinylamino)-pentanoicacid ethyl ester

Freshly ground KF (1.174, 20.21 mmol) was added to a solution of(R)-3-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-5-methoxy-3-((S)-2-methyl-propane-2-sulfinylamino)-pentanoicacid ethyl ester (6.10 g, 10.11 mmol) and acetic acid (1.157 ml, 20.21mmol) in THF (39.8 ml). DMF (39.8 ml) was added and the suspension wasstirred at rt. After 6 h the reaction mixture was diluted with ethylacetate and washed with sat. sodium bicarbonate solution and brine,dried over sodium sulfate, filtered and evaporated. The crude product(4.85 g, 98% yield) was used without purification in the next step.

TLC (cyclohexane/ethyl acetate 1:1): R_(f)=0.33;

LC-MS: Rt_(H1)=1.11 min (100%, ESI+−MS: m/z 489 [(M+H)⁺, 1Br], 491);

¹H-NMR (400 MHz, CDCl₃): δ 7.56-7.48 (m, 1H), 7.41-7.30 (m, 1H), 6.54(br. s, 1H), 4.25-4.05 (m, 2H), 3.77-3.64 (m, 1H), 3.34-3.22 (m, 1H),3.15 (s, 3H), 3.08-2.97 (m, 1H), 2.94-2.86 (m, 1H), 1.34 (s, 9H), 1.18(t, J=7.3 Hz, 3H).

e) (S)-2-Methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-hydroxy-1-(2-methoxy-ethyl)-propyl]-amide

To a solution of(R)-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-5-methoxy-3-((S)-2-methyl-propane-2-sulfinylamino)-pentanoicacid ethyl ester (2.4 g, 4.90 mmol) in THF (38 ml) was addedlithiumborohydride (214 mg, 9.81 mmol) in 2 portions. The slightlyexothermic reaction was stirred for 6 hours at room temperature. Crushedice was added carefully and the reaction mixture was diluted with ethylacetate. The organic phase was washed with water and brine, dried oversodium sulfate, filtered and evaporated. The crude yellowish resin (2.05g) was chromatographed over silica gel (Redisep column 40 g,cyclohexane/ethyl acetate 4:6) to give the title compound as acolourless resin. 1.50 g (68.4% yield).

TLC (cyclohexane/ethyl acetate 1:1): R_(f)=0.13;

LC-MS: Rt_(H1)=0.84 min (100%, ESI+−MS: m/z 447 [(M+H)⁺, 1Br], 449);

¹H-NMR (400 MHz, CDCl₃): δ 7.55-7.45 (m, 1H), 7.37-7.29 (m, 1H),6.34-6.25 (br. s, 1H), 3.95-3.63 (m, 2+1H), 3.40-3.27 (m, 1H), 3.18 (s,3H), 3.05-2.94 (m, 1H), 2.84-2.73 (m, 1H), 2.19-2.11 (m, 1H, OH), 1.35(s, 9H).

f)(R)-3-Amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-5-methoxy-pentan-1-ol

To a solution of (S)-2-methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-hydroxy-1-(2-methoxy-ethyl)-propyl]-amide(1.50 g, 3.33 mmol) in methanol (8.4 ml) was added 2M HCl in diethylether (6.56 ml, 13.11 mmol). The reaction mixture was stirred for 1.5 hat room temperature. 7 M ammonia in methanol (2.7 ml) was added to thereaction mixture and the resulting colourless suspension was evaporatedin vacuo. The remaining solid was triturated with warm dichloromethane,cooled to rt, filtered and rinsed with dichloromethane. The filtrate wasevaporated affording the title compound which was used withoutpurification in the next step. 1.42 g colourless, viscous oil. 100%yield.

TLC (cyclohexane/ethyl acetate 4:6): R_(f)=0.41;

LC-MS: Rt_(H1)=0.52 min (100%, ESI+−MS: m/z 343 [(M+H)⁺, 1Br], 345);

¹H-NMR (400 MHz, CDCl₃): δ 7.52 (dd, J=3.1, 8.4 Hz, 1H), 7.34 (dd,J=8.4, 9.9 Hz, 1H), 4.23-4.06 (m, 1H), 3.81 (s, 1H+OH), 3.66-3.56 (m,1H), 3.30-3.21 (m, 1H), 3.17 (s, 3H), 2.77-2.66 (m, 1H), 2.57-2.43 (m,1H).

g)N—[(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-2-yl]-4-nitro-benzamide

To a solution of(R)-3-amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-5-methoxy-pentan-1-ol(1.15 g, 3.35 mmol) in THF (27.9 ml) was addednitrobenzoyl-isothiocyanate (767 mg, 3.69 mmol). After stirring at rtfor 4 hr DCC (760 mg, 3.69 mmol) and triethylamine (34.1 mg, 0.337 mmol)was added. Stirring was continued at rt for 19 hr and finally, thereaction mixture was kept at 70° C. for 5 h. The yellow-orange solutionwas cooled and evaporated in vacuo. The crude product (2.7 g) waschromatographed over silica gel (Redisep column 120 g, cyclohexane/ethylacetate 7:3) to give the title compound as a light yellow foam. 650 mg(35.6% yield).

TLC (cyclohexane/ethyl acetate 7:3): R_(f)=0.17;

LC-MS: Rt_(H1)=1.15 min (95%, ESI+−MS: m/z 517 [(M+H)⁺, 1Br], 519);

¹H-NMR (400 MHz, CDCl₃): δ 12.07 (br. s, 1H), 8.49 (d, J=9.0 Hz, 2H),8.29 (d, J=8.9 Hz, 2H), 7.68-7.58 (m, 1H), 7.49-7.40 (m, 1H), 4.59-4.42(m, 1H), 4.35-4.19 (m, 1H), 3.87-3.72 (m, 1H), 3.54-3.39 (m, 1H), 3.35(s, 3H), 3.02-2.88 (m, 1H), 2.71-2.57 (m, 1H).

h)(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-2-ylamine

A suspension ofN—[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H[1,3]oxazin-2-yl]-4-nitro-benzamide(640 mg, 1.237 mmol) and potassium carbonate (513 mg, 3.71 mmol) inmethanol (18.7 ml) was stirred for 22 h at rt. The resulting yellowsolution was evaporated, diluted with ethyl acetate and washed withwater and brine, dried over sodium sulfate, filtered and evaporated. 400mg yellow solid (88% yield). The crude product was used in the next stepwithout purification.

TLC (cyclohexane/ethyl acetate 1:1): R_(f)=0.14;

LC-MS: Rt_(H1)=0.59 min (100%, ESI+−MS: m/z 368 [(M+H)⁺, 1Br], 370);

¹H-NMR (400 MHz, CDCl₃): δ 7.53-7.43 (m, 1H), 7.28 (s, 1H), 4.35-4.18(m, 1H), 4.14-4.01 (m, 1H), 3.71-3.62 (m, 1H), 3.53-3.40 (m, 1H), 3.30(s, 3H), 3.26-3.10 (m, 1H), 3.05-2.93 (m, 1H), 2.32-2.14 (br. s, 1H,NH), 1.77-1.47 (br. s, 2H, NH plus res. water).

i)[Bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-2-yl]-amine

To a solution of(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-2-ylamine(200 mg, 0.543 mmol) and triethylamine (110 mg, 1.087 mmol) indichloromethane (5.4 ml) was added solid 4,4′-dimethoxytrityl chloride(202 mg, 0.598 mmol) under argon atmosphere. The green solution wasstirred at rt for 16 hrs and was then evaporated in vacuo. The crudeproduct was taken up with ethyl acetate and washed with aqueous citricacid, aqueous sodium bicarbonate solution, water and brine. The organicphase was dried over sodium sulfate, filtered and evaporated. The crudeproduct (380 mg) was chromatographed over silica gel (Redisep column 12g, cyclohexane/ethyl acetate 8:2) to give the title compound as acolourless foam. 339 mg (93% yield).

TLC (cyclohexane/ethyl acetate 8:2): R_(f)=0.29;

LC-MS: Rt_(H1)=1.23 min (100%, ESI+−MS: m/z 670 [(M+H)⁺, 1Br], 672);

¹H-NMR (400 MHz, CDCl₃): δ 7.49-7.16 (m, 11H), 6.87-6.78 (m, 4H),5.41-5.28 (m, 1H), 3.87-3.59 (m, 9H), 3.07 (m, 4H), 2.99-2.85 (m, 1H),2.74-2.60 (m, 1H).

j) 5-Cyano-3-methyl-pyridine-2-carboxylic acid{6-[(R)-2-{[bis-(4-methoxy-phenyl)-phenyl-methyl]-amino}-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide

A degassed mixture of[bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-2-yl]-amine(330 mg, 0.492 mmol), 5-cyano-3-methyl-pyridine-2-carboxylic acid amide(95 mg, 0.591 mmol), rac-trans-N,N′-dimethylcyclohexane-1,2-diamine(21.65 mg, 0.148 mmol), potassium carbonate (150 mg, 1.083 mmol) andcopper iodide (28.1 mg, 0.148 mmol) was refluxed under argon in dioxane(12.3 ml) for 20 hrs. The reaction mixture was evaporated, taken up inethyl acetate and washed with aqueous sodium bicarbonate solution, waterand brine, dried over sodium sulfate, filtered and evaporated to give406 mg red-brown foam. The crude product was chromatographed over silicagel (Redisep column 12 g, toluene/ethyl acetate 8:2) to give the titlecompound as a pinky foam. 152 mg (37.4% yield).

TLC (toluene/ethyl acetate 8:2): R_(f)=0.37;

LC-MS: Rt_(H1)=1.22 min (91% pure; ESI+−MS: 751).

k) 5-Cyano-3-methyl-pyridine-2-carboxylic acid{6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide

A solution of 5-cyano-3-methyl-pyridine-2-carboxylic acid{6-[(R)-2-{[bis-(4-methoxy-phenyl)-phenyl-methyl]-amino}-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide(146 mg, 0.194 mmol), TFA (0.989 ml, 12.83 mmol) and triethylsilane(0.093 ml, 0.583 mmol) in dichloromethane (1.9 ml) was stirred at rt for18 hours. The reaction mixture was evaporated and the residue dilutedwith ethyl acetate, washed with sat. aqueous sodium bicarbonatesolution, water and brine, dried over sodium sulfate, filtered andevaporated. 142 mg colourless resin. The product was chromatographedover a preparative silica gel plate (2 mm, 20×20 cm, Merck,dichloromethane/methanol 95:5) to give the title compound as acolourless foam. 74 mg (85% yield).

TLC (dichloromethane/methanol 95:5, silica gel, UV 254): R_(f)=0.28;

LC-MS: Rt_(H1)=0.76 min (100% pure; ESI+−MS: 449 [(M+H)⁺]);

¹H-NMR (400 MHz, DMSO-d₆): δ=10.70 (br. s, 1H, NH), 9.00 (br. s, 1H),8.45 (br. s, 1H), 8.30-8.13 (m, 1H), 7.84-7.66 (m, 1H), 5.88 (br. s,3H), 4.45-4.25 (m, 1H), 4.19-4.00 (m, 1H), 3.62-3.44 (m, 1H), 3.27-3.18(m, 1H), 3.16 (s, 3H), 2.96-2.83 (m, 1H), 2.61 (s, 3H), 2.00-1.88 (m,1H).

Examples 5-6

The compounds listed in Table 3 were prepared by a procedure analogousto that used in Example 4. However, for Example 5(R)-tert.-butylsulfinamide was used to form the sulfoximine in step 4b.

TABLE 3 MS [m/z; Example Compound ¹H-NMR (solvent; δ) (M + 1)⁺] 5

(400 MHz, CDCl₃): δ 10.69 (br · s, 1H), 8.92- 8.82 (m, 1H), 8.55-8.43(m, 1H), 7.96-7.87 (m, 1H), 7.68-7.58 (m, 1H), 4.61-4.45 (m, 1H),4.31-4.17 (m, 1H), 3.65-3.56 (m, 2H), 3.32 (s, 3H), 3.01- 2.88 (m, 1H),2.81 (s, 3H), 2.58-2.43 (m, 1H) LCMS: Rt_(H3) = 0.75 [M + 1] = 4495-Cyano-3-methyl-pyridine-2-carboxylic acid{6-[(S)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5- fluoro-pyridin-2-yl}-amide 6

(400 MHz, CDCl₃): δ 10.47 (br · s, 1H), 8.82 (s, 1H), 8.41 (dd, 1H),8.06 (s, 1H), 7.49 (t, 1H), 4.25-4.33 (d, 1H), 3.97-4.20 (m, 1H),3.42-3.56 (m, 2H), 3.19 (s, 3H), 2.78-2.92 (m, 1H), 2.15-2.31 (m, 1H)LCMS: Rt_(H2) = 0.81 [M + 1] = 514.03-Chloro-5-trifluoromethyl-pyridine-2- carboxylic acid{6-[(R)-2-amino-5,5-difluoro- 4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide

Example 7 3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

a)[Bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-A-amine

(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazine-2-ylamine(5 g, 15.43 mmol, Example 1 intermediate h) was dissolved in DCM (154ml) under argon, triethylamine (4.30 mL, 30.9 mmol) and4,4′-dimethoxytrityl chloride (5.75 g, 16.97 mmol) were added and thereaction mixture was stirred at rt for 18 hours. The solvent was removedin vacuo and the residue was taken up in ethyl acetate. The organiclayer was washed with aq 10% citric acid, water, aqueous saturatedsodium bicarbonate solution and brine, dried over sodium sulfate,filtered and concentrated. The crude product was chromatographed oversilica gel (Redisep column 120 g, cyclohexane/ethyl) to give the titlecompound: 8.16 g (69.2% yield).

TLC (cyclohexane/ethyl acetate 3:1, silica gel, UV 254): R_(f)=0.45;

LC-MS: Rt_(H2)=1.37 min; (ESI+−MS: m/z 626 [(M+H)⁺,1Br]; 628);

¹H-NMR (400 MHz, DMSO-d₆): δ 7.71 (dd, 1H), 7.64 (dd, 1H), 7.32-7.08 (m,9H), 6.86 (s, 1H), 6.81-6.77 (m, 4H), 4.07-4.05 (m, 1H), 4.02-3.98 (m,1H), 3.71 (s, 6H), 1.05 (br. s., 3H).

b)[(R)-4-(6-Amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-[bis-(4-methoxy-phenyl)-phenyl-methyl]-amine

To a solution of[bis-(4-methoxy-phenyl)-phenyl-methyl]-[(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-amine(23.4 g, 28.8 mmol) in ammonia (173 ml, 1.21 mol, 7M in methanol) in amicrowave vial was added ethylene glycol (240 ml) and methanol (240 ml).Copper oxide Cu₂O (1.21 g, 8.46 mmol) was added and the vial was sealed.The reaction mixture was stirred at 80° C. for 43 hours. The coldreaction mixture was diluted with ethyl acetate and washed with water,aqueous ammonia and brine. The organic layer was dried over sodiumsulfate, filtered and evaporated. The crude product was chromatographedover silica gel (400 g, dichloromethane/methanol 98:2+0.2% ammonia) togive the title compound: 4.29 g (25% yield).

TLC (dichloromethane/methanol 95:5+0.5% ammonia, silica gel, UV 254):R_(f)=0.29;

LC-MS: Rt_(H2)=1.03 min; (ESI+−MS: m/z 563 [(M+H)⁺]);

¹H-NMR (400 MHz, DMSO-d₆): δ 7.25-7.32 (m, 2H) 7.10-7.24 (m, 8H) 6.77(d, 4H) 6.59 (s, 1H) 6.41 (dd, 1H) 5.77 (d, 2H) 4.09-4.22 (m, 1H)3.91-4.01 (m, 1H) 3.70 (s, 6H) 0.97 (br. s., 3H).

c) 3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-5,5-difluoro-2-{[(4-methoxy-phenyl)-(3-methoxy-phenyl)-phenyl-methyl]-amino}-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

[(R)-4-(6-amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-[bis-(4-methoxy-phenyl)-phenyl-methyl]-amine(250 mg, 0.444 mmol), 3-chloro-5-(trifluoromethyl)-picolinic acid (120mg, 0.533 mmol) and HOAt (109 mg, 0.800 mmol) were dissolved in DMF(4.44 ml) under argon. EDC×HCl (128 mg, 0.667 mmol) was added and thereaction mixture was stirred at rt for 18 hours. The reaction mixturewas diluted with ethyl acetate, washed with water and brine, dried oversodium sulfate, filtered and concentrated. The crude product waschromatographed over silica gel (Redisep column 12 g, cyclohexane/ethylacetate) to give the title compound: 100 mg (29.2% yield).

LC-MS: Rt_(H2)=1.43 min; (96% purity; ESI+−MS: m/z 770 [(M+H)⁺,1Cl];772);

¹H-NMR (400 MHz, DMSO-d₆): δ 11.22 (s, 1H), 9.08 (s, 1H), 8.72 (s, 1H),8.16 (dd, 1H), 7.71 (dd, 1H), 7.30-7.24 (m, 2H), 7.23-7.10 (m, 7H),6.81-6.74 (m, 5H), 4.33-4.23 (m, 1H), 4.08-4.00 (m, 1H), 3.70 (s, 6H),1.06 (br. s, 3H).

d) 3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-5,5-difluoro-2-{[(4-methoxy-phenyl)-(3-methoxy-phenyl)-phenyl-methyl]-amino}-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide(80 mg, 0.104 mmol) was dissolved in dichloromethane (0.1039 ml), TFA(80.0 μl, 1.04 mmol) was added and the reaction mixture was stirred atrt for 18 hours. The reaction mixture was poured onto a mixture of iceethyl acetate and NH₄OH (w=25%). The organic layer was washed withwater, brine, dried over sodium sulfate, filtered and concentrated. Thecrude product was chromatographed over silica gel (column 4 g,dichloromethane/methanol 95:5+0.5% ammonia) to give the title compound:32 mg (65.9% yield).

LC-MS: Rt_(H1)=0.79 min; (100% purity; ESI+−MS: m/z 468 [(M+H)⁺,1Cl];470);

¹H-NMR (400 MHz, CDCl₃): δ 10.21 (br. s, 1H), 8.86 (d, 1H), 8.40 (dd,1H), 8.17 (d, 1H), 7.53 (dd, 1H), 4.21-4.13 (m, 4H), 1.83 (t, 3H).

Example 7a Alternative synthesis of3-chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amidea)(R)-4-(6-Bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine

The (+)-campher sulfonic acid salt of(R)-3-amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol(12.75 g, 23.99 mmol) was partitioned between TBME and aq. Na₂CO₃(w=10%), the layers were separated, the aq. layer was extracted withTBME, the organic layer was extracted with sat. aq. NaCl. The combinedorganic layers were dried with Na₂CO₃, the solvent evaporated to yieldthe free base as white crystals.

To a solution of(R)-3-amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol(9.49 g, 31.7 mmol) in EtOH (256 ml) was added NaHCO₃ (1.066 g, 12.69mmol) and cyanogen bromide (10.08 g, 95 mmol) and the mixture was warmedto 85° C. over night. After cooling to rt the solvent was evaporated andthe residue taken up in 1N HCl and TBME, the layers were separated andthe organic layer was washed with 1N HCl. The aq. layers were combined,basified by addition of solid Na₂CO₃ and extracted with TBME (2×). Thecombined TBME extracts were washed with sat. aq. NaCl, dried with K₂CO₃to provide the desired product as yellow resin. This material was usedfor the next step without further purification.

HPLC: Rt_(H5)=2.716 min; ESIMS [M+H]⁺=324.0/326.0; ¹H-NMR (600 MHz,DMSO-d₆): δ 7.76-7.59 (m, 2H), 5.85 (s, 2H), 4.43-4.30 (m, 1H),4.24-4.10 (m, 1H), 1.63 (br. s, 3H).

b)(R)-4-(6-Amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine

To a solution of(R)-4-(6-bromo-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine(8.73 g, 23.17 mmol) in ethylene glycol (139 ml) and aq. NH₃ (w=25%, 108ml) in an autoclave was added copper(I) oxide (497 mg, 3.47 mmol) andthe mixture was warmed to 60° C. over night. After cooling to rt themixture was extracted with EtOAc, the organic layer was washed with aq.NH₃ (w=12%, 2×), the combined organic layers were washed with sat. aq.NaCl, dried with Na₂SO₄ and evaporated. The residue was dissolved inTBME and extracted with 1N HCl (2×). The combined aq. layers werebasified by addition of solid Na₂CO₃ some NaCl was added and the aq.solution extracted with DCM (4×). The combined DCM extracts were driedwith K₂CO₃ and evaporated to provide the title compound as greyishresin. The crude material was used for the next step without furtherpurification.

HPLC: Rt_(H5)=2.584 min; ESIMS [M+H]⁺=261.0; ¹H-NMR (600 MHz, DMSO-d₆):δ 7.23 (dd, 1H), 6.40 (dd, 1H), 5.77 (s, 2H), 5.63 (s, 2H), 4.29-4.15(m, 2H), 1.56 (s, 3H).

c)[(R)-4-(6-Amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-carbamicacid tert-butyl ester

To a solution of(R)-4-(6-amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-ylamine(4.53 g, 17.41 mmol) in DCM (46 ml) was added DIPEA (4.26 ml, 24.37mmol) and Boc₂O (4.56 g, 20.89 mmol) and the mixture was warmed to 40°C. over night. The solvent was evaporated (at 34° C.) and the residuewas purified by chromatography on silica gel (cyclohexane/[EtOAc/MeOH95:5] 4:1 to 1:1) to provide the title compound as colorless foam. HPLC:Rt_(H5)=3.001 min; ESIMS [M+H]⁺=361.2; ¹H-NMR (600 MHz, CDCl₃): δ 7.26(t, 1H), 6.51 (d, 1H), 4.51 (br. s, 2H), 4.40-4.29 (m, 2H), 1.91 (s,3H), 1.52 (s, 9H).

d)((R)-4-{6-[(3-Chloro-5-trifluoromethyl-pyridine-2-carbonyl)-amino]-3-fluoro-pyridin-2-yl}-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-carbamicacid tert-butyl ester

To a solution of[(R)-4-(6-amino-3-fluoro-pyridin-2-yl)-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl]-carbamicacid tert-butyl ester (134 mg, 0.372 mmol) in DMF (1.3 ml) was added3-chloro-5-trifluoromethyl-pyridine-2-carboxylic acid (101 mg, 0.446mmol) and HOAt (91 mg, 0.669 mmol). The mixture was cooled to 0° C.,EDC*HCl (107 mg, 0.558) was added and the mixture stirred for 1 h whileallowing to warm to rt. To the reaction mixture was added TBME andwater, the layers were separated and the aq. layer extracted with TBME.The combined organic layers were washed with sat. aq. NaHCO₃, sat. aq.NaCl, dried with MgSO₄ and evaporated. The residue was purified bychromatography on silica gel (cyclohexane/EtOAc 6:1 to 5:1) to providethe title compound as colorless solid.

HPLC: Rt_(H7)=2.920 min; ESIMS [M+H]⁺=568.0/570,0; ¹H-NMR (600 MHz,DMSO-d₆): δ 11.25 (s, 1H), 9.65 (s, 1H), 9.08 (br. s, 1H), 8.72 (br. s,1H), 8.23 (d, 1H), 7.83 (t, 1H), 4.57-4.41 (m, 2H), 1.72 (s, 3H), 1.40(s, 9H).

e) 3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

To a solution of((R)-4-{6-[(3-chloro-5-trifluoromethyl-pyridine-2-carbonyl)-amino]-3-fluoro-pyridin-2-yl}-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-carbamicacid tert-butyl ester (180 mg, 0.317 mmol) in DCM (1.5 ml) was added TFA(0.5 ml) and the mixture was stirred at rt for 1 h. The reaction mixturewas poured on 10% aq. Na₂CO₃, more DCM was added and the layers wereseparated. The aq. phase was extracted with DCM (3×), the combined DCMphases were dried with K₂CO₃ and evaporated to provide the titlecompound as colorless solid.

HPLC: Rt_(H8)=3.001 min; ESIMS [M+H]⁺=468.0/470,0; ¹H-NMR (600 MHz,CDCl₃): δ 10.22 (br. s, 1H), 8.87 (s, 1H), 8.41 (dd, 1H), 8.18 (s, 1H),7.53 (t, 1H), 4.33-4.13 (m, 4H), 1.85 (s, 3H).

Examples 8 to 21

The compounds listed in Table 4 were prepared by a procedure analogousto that used in Example 7.

TABLE 4 MS [m/z; Example Compound ¹H-NMR (solvent; δ) (M + 1)⁺]  8

(400 MHz, DMSO-d₆): δ 10.28 (s, 1H), 8.38 (s, 1H), 8.15 (dd, 1H), 8.10(br · s, 2H), 7.80 (dd, 1H), 5.79 (s, 2H), 4.40-4.18 (m, 2H), 1.67 (s,3H) LCMS: Rt_(H2) = 0.78 [M + 1] = 450.13-Amino-5-trifluoromethyl-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro- 4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide  9

(400 MHz, DMSO-d₆): δ 10.97 (br · s, 1H), 8.73 (s, 1H), 8.45 (s, 1H),8.17 (dd, 1H), 7.75 (dd, 1H), 5.75 (br · s, 2H), 4.36-4.28 (m, 2H), 1.66(s, 3H) LCMS: Rt_(H2) = 0.75; [M + 1] = 434.0/ 436.03,5-Dichloropyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro- pyridin-2-yl]-amide 10

(400 MHz, DMSO-d₆): δ 9.93 (s, 1H), 8.16 (dd, 1H), 7.89 (br · s, 2H),7.78-7.73 (m, 1H), 7.73 (s, 1H), 5.78 (s, 2H), 5.05 (q, 2H), 4.36-4.27(m, 1H), 4.25-4.16 (m, 1H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.43; [M + 1] =480.5 3-Amino-5-(2,2,2-trifluoro-ethoxy)pyrazine- 2-carboxylic acid[6-((R)-2-amino-5,5- difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 11

(400 MHz, DMSO-d₆): δ 9.96 (br · s., 1H), 8.19 (dd, 1H), 8.03- 7.75 (m,3H), 7.67 (s, 1H), 6.46 (tt, 1H), 4.63 (td, 2H), 4.42-4.31 (m, 2H), 1.71(br · s, 3H) LCMS: Rt_(H2) = 0.78; [M + 1] = 462.13-Amino-5-(2,2-difluoro-ethoxy)-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro- 4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 12

(400 MHz, DMSO-d₆): δ 10.14 (br · s, 1H), 8.28 (d, 1H), 7.96 (t, 1H),7.79 (br · s, 2H), 7.56 (s, 1H), 4.96 (br · s, 1H), 4.80 (br · s, 1H),4.68 (t, 1H), 4.56 (t, 1H), 4.43 (t, 2H), 2.16 (dquin, 2H), 1.91 (br ·s, 3H) LCMS: Rt_(H2) = 0.80; [M + 1] = 458.13-Amino-5-(3-fluoro-propoxy)-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro- 4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 13

(400 MHz, CDCl3): δ 10.49 (s, 1H), 8.36 (dd, 1H), 8.17 (d, 1H), 7.45(dd, 1H), 7.08 (dd, 1H), 4.40 (br · s, 2H), 4.28-4.08 (m, 2H), 3.92 (s,3H), 2.79 (s, 3H), 1.85 (t, 3H) LCMS: Rt_(H2) = 0.77; [M + 1] = 411.15-Methoxy-3-methyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro- pyridin-2-yl]-amide 14

(400 MHz, DMSO-d₆): δ 10.26 (s, 1H), 8.19 (dd, 1H), 7.95 (d, 1H), 7.75(dd, 1H), 7.36 (d, 1H), 7.09 (br · s, 2H), 5.79 (s, 2H), 4.39 (s, 2H),4.37- 4.26 (m, 1H), 4.26- 4.12 (m, 1H), 3.32 (s, 3H), 1.67 (s, 3H) LCMS:Rt_(H2) = 0.78; [M + 1] = 450.1 3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]- amide 15

(400 MHz, DMSO-d₆): δ 9.96 (s, 1H), 8.17 (dd, 1H), 7.89 (br · s, 2H),7.76 (dd, 1H), 7.71 (s, 1H), 6.11 (d, 2H), 5.78 (s, 2H), 4.37- 4.27(m,1H), 4.26- 4.15 (m, 1H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.72; [M + 1] =430.1 3-Amino-5-fluoromethoxy-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro- 4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 16

(400 MHz, DMSO-d₆): δ 9.90 (s, 1H), 8.17 (d, 1H), 7.98-7.68 (m, 3H),7.60 (s, 1H), 5.79 (s, 2H), 4.44 (br · s, 2H), 4.36-4.27 (m, 1H), 4.25-4.16 (m, 1H), 3.69 (br · s, 2H), 3.32 (s, 3H), 1.66 (br · s, 3H) LCMS:Rt_(H2) = 0.74; [M + 1] = 456.2 3-Amino-5-(2-methoxy-ethoxy)-pyrazine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)- 5-fluoro-pyridin-2-yl]-amide17

(400 MHz, DMSO-d₆): δ 10.26 (s, 1H), 8.19 (dd, 1H), 7.91 (d, 1H), 7.75(dd, 1H), 7.32 (d, 1H), 7.09 (br · s, 2H), 5.79 (br · s, 2, H), 5.46 (t,1H), 4.44-4.26 (m, 3H), 4.26-4.13 (m, 1H), 1.67 (s, 3H) LCMS: Rt_(H2) =0.68; [M + 1] = 435.2 3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 18

(400 MHz, DMSO-d₆): δ 10.15 (s, 1H), 8.18 (dd, 1H), 7.91 (dd, 1H), 7.75(dd, 1H), 7.25 (br · s, 2H), 7.11 (dd, 1H), 5.78 (s, 2H), 4.32 (td, 1H),4.20 (td, 1H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.71; [M + 1] = 399.23-Amino-5-fluoro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro- pyridin-2-yl]-amide 19

(400 MHz, DMSO-d₆): δ 10.18 (s, 1H), 8.18 (dd, 1H), 7.92 (d, 1H), 7.76(dd, 1H), 7.39 (d, 1H), 7.19 (br · s, 2H), 5.79 (br · s, 2H), 4.39- 4.09(m, 2H), 1.67 (s, 3H) LCMS: Rt_(H2) = 0.77; [M + 1] = 415.13-Amino-5-chloro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro- pyridin-2-yl]-amide 20

(400 MHz, CDCl3): δ 10.44 (br · s, 1H), 8.61 (d, 1H), 8.46 (d, 1H), 7.90(d, 1H), 7.53 (t, 1H), 7.50-7.44 (m, 1H). 4.92 (br · s, 2H), 4.39-4.17(m, 2H), 1.91 (br · s, 3H) LCMS: Rt_(H2) = 0.67; [M + 1] = 400.13-Chloro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 21

(400 MHz, CDCl3): δ 10.45 (br · s, 1H), 8.62 (d, 1H), 8.47 (dd, 1H),7.91 (d, 1H), 7.56 (dd, 1H), 4.47-4.24 (m, 4H), 3.48 (s, 3H), 1.95 (br ·s, 3H) LCMS: Rt_(H2) = 0.80; [M + 1] = 468.13-Chloro-5-(3-methoxy-prop-1- ynyl)pyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

Examples 22 to 36

The compounds presented below in Table 5 were also prepared by aprocedure analogous to that used in Example 7. Examples 26 and 27 wereseparated after the deprotection step by prep. TLC (DCM/MeOH 95:5).

TABLE 5 MS [m/z; Example Compound Structure ¹H-NMR (solvent; δ) (M +1)⁺] 22

(400 MHz, DMSO-d₆): δ 10.44 (br · s, 1H), 8.28-8.13 (m, 2H), 8.02-7.84(m, 3H), 6.98 (t, 1H, CHF2), 4.66-4.57 (m, 2H), 1.82 (s, 3H) LCMS:Rt_(H2) = 0.69; [M + 1] = 432.2 3-Amino-5-difluoromethyl-pyrazine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide23

(400 MHz, DMSO-d₆): δ 9.91 (s, 1H), 8.17 (dd, 1H), 7.87 (br · s, 2H),7.74 (d, 1H), 7.76 (d, 1H), 7.62 (s, 1H), 5.83 (br · s, 1H), 4.66- 4.53(m, 2H), 4.40-4.14 (m, 2H), 4.06-3.97 (m, 2H), 1.66 (s, 3H) LCMS:Rt_(H2) = 0.79; [M + 1] = 460.1/ 462.13-Amino-5-(2-chloro-ethoxy)-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl}-5- fluoro-pyridin-2-yl]-amide24

(400 MHz, DMSO-d₆): δ 10.68 (s, 1H), 8.46 (br s, 1H), 8.18 (d, 1H), 7.89(s, 1H), 7.74 (t, 1H), 7.08 (d, 1H), 6.85 (d, 1H), 6.47 (t, 1H, CHF2),4.69-4.51 (m, 2H), 4.43-4.17 (m, 2H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.79;[M + 1] = 480.1/ 482.1 3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide25

(400 MHz, DMSO-d₆): δ 10.00 (s, 1H), 8.21 (d, 1H), 7.90 (br · S, 2H),7.82 (t, 1H), 7.63 (s, 1H), 4.91-4.82 (m, 1H), 4.78-4.69 (m, 1H),4.65-4.57 (m, 1H), 4.56-4.49 (m, 1H), 4.41 (br · s, 2H), 1.75 (s, 3H)LCMS: Rt_(H2) = 0.76; [M + 1] = 444.23-Amino-5-(2-fluoro-ethoxy)-pyrazine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide26

(400 MHz, DMSO-d₆): δ 10.80 (s, 1H), 8.53 (s, 1H), 8.18 (d, 1H), 7.97(s, 1H), 7.75 (t, 1H), 6.13 (s, 1H), 6.00 (s, 1H), 5.78 (br · s, 2H),4.46-4.17 (m, 2H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.74; [M + 1] = 448.1/450.2 3-Chloro-5-fluoromethoxy-pyridine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide27

(400 MHz, DMSO-d₆): δ 10.60 (s, 1H), 8.38 (s, 1H), 8.18 (d, 1H),7.83-7.67 (m, 2H), 5.82 (br · s, 1H), 4.41- 4.15 (m, 4H), 1.66 (s, 3H),1.38 (t, 3H) LCMS: Rt_(H2) = 0.81; [M + 1] = 444.1/ 446.33-Chloro-5-ethoxy-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin- 2-yl]-amide 28

(600 MHz, DMSO-d₆): δ 9.90 (s, 1H), 8.17 (d, 1H), 7.90 (br · s, 2H),7.75 (t, 1H), 7.56 (s, 1H), 5.82 (br · s, 2H), 4.32 (q, 1H), 4.20 (q,1H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.79; [M + 1] = 431.33-Amino-5-(penta-deutero-ethoxy)-pyrazine- 2-carboxylic acid[6-((R)-2-amino-5,5- difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 29

(600 MHz, DMSO-d₆): δ 10.16 (s, 1H), 8.18 (d, 1H), 7.90 (s, 1H), 7.77(t, 1H), 7.62 (br · s, 2H), 5.85 (br · s, 1H), 4.34 (q, 1H), 4.22 (q,1H), 3.71 (t, 2H), 3.25 (s, 3H), 2.92 (t, 2H), 1.67 (s, 3H) LCMS:Rt_(H2) = 0.69; [M + 1] = 440.3 3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide30

(400 MHz, DMSO-d₆): δ 10.27 (s, 1H), 8.81 (s, 1H), 8.14-8.01 (m, 1H),7.94 (s, 1H), 7.84-7.68 (m, 2H), 4.33 (t, 2H), 1.66 (s, 3H) LCMS:Rt_(H2) = 0.74; [M + 1] = 439.1/ 441.14-Chloro-1-difluoromethyl-1H-pyrazole-3- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide31

(400 MHz, DMSO-d₆): δ 10.22 (s, 1H), 8.37 (d, 1H), 8.18 (dd, 1H), 7.97(d, 1H), 7.78 (dd, 1H), 7.65 (br · s, 2H), 5.85 (br · s, 2H), 4.42- 4.15(m, 2H), 1.68 (s, 3H) LCMS: Rt_(H2) = 0.60; [M + 1] = 382.23-Amino-pyrazine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 32

(400 MHz, DMSO-d₆): δ 10.99 (s, 1H), 8.68 (s, 1H), 8.23 (s, 1H), 8.17(d, 1H), 7.75 (t, 1H), 5.76 (br · s, 2H), 5.52 (t, 1H), 4.39 (d, 2H),4.32 (br · s, 2H), 1.66 (s, 3H) LCMS: Rt_(H2) = 0.68; [M + 1] = 454.2/456.1 3-Chloro-5-(3-hydroxy-prop-1-ynyl)-pyridine- 2-carboxylic acid[6-((R)-2-amino-5,5- difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 33

(400 MHz, DMSO-d₆): δ 10.34 (s, 1H), 8.20 (dd, 1H), 8.07 (s, 1H), 7.77(dd, 1H), 7.48 (s, 1H), 7.24 (br · s, 2 H), 7.14 (t, 1 H, CHF2), 5.80(s, 2H), 4.39- 4.14 (m, 2H), 1.67 (s, 3H) LCMS: Rt_(H2) = 0.74; [M + 1]= 431.2 3-Amino-5-difluoromethyl-pyridine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide34

(400 MHz, DMSO-d₆): δ 9.99 (s, 1H), 8.13 (dd, 1H), 7.97 (br · s, 2H),7.80 (dd, 1H), 5.83 (br · s, 2H), 4.43- 4.17 (m, 2H), 2.05 (t, 3H), 1.68(s, 3H) LCMS: Rt_(H2) = 0.81; [M + 1] = 480.2/ 482.23-Amino-6-chloro-5-(1,1-difluoro-ethyl)- pyrazine-2-carboxylic acid[6-((R)-2-amino- 5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 35

(600 MHz, DMSO-d₆): δ 10.41 (s, 1H), 9.26 (s, 1H), 8.64 (dd, 1H), 8.35(d, 1H), 8.23 (d, 1H), 7.82 (t, 1H), 5.83 (br · s, 2H), 4.40-4.20 (m,2H), 1.68 (s, 3H) LCMS: Rt_(H2) = 0.66; [M + 1] = 391.25-Cyano-pyridine-2-carboxylic acid [6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide 36

(600 MHz, CDCl₃): δ 10.30 (br · s, 1H), 8.74 (s, 1H), 8.49-8.36 (m, 1H),8.03 (s, 1H), 7.52 (t, 1H), 4.33 (br · s, 1H), 4.25-4.13 (m, 2H), 2.04(t, 3H), 1.85 (s, 3H) LCMS: Rt_(H8) = 2.981; [M + 1] = 464.0/ 466.03-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2- carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5- fluoro-pyridin-2-yl]-amide

Example 37 3-Amino-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide

To a solution of3-amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide[Example 34] (54 mg, 0.113 mmol) in MeOH/THF (1:1, 10 ml) was added Pd/C10% (BASF 4505 D/R E, 12 mg) and the mixture was set under an hydrogenatmosphere. After 2.5 h more Pd/C 10% (BASF 4505 D/R E, 11 mg) was addedand the hydrogenation continued for another 2.5 h. The reaction mixturewas filtered through a pad of Celite, washed with MeOH and the solventevaporated. The residue was purified by chromatography on silica gel(DCM to DCM/MeOH 9:1) to provide the title compound as yellow foam.

HPLC: Rt_(H2)=0.76 min; ESIMS [M+H]⁺=446.2; ¹H-NMR (400 MHz, DMSO-d₆): δ10.25 (s, 1H), 8.22 (s, 1H), 8.17 (dd, 1H), 7.92 (s, 2H), 7.79 (dd, 1H),5.82 (br. s, 1H), 4.44-4.14 (m, 2H), 2.00 (t, 3H), 1.68 (s, 3H)

Preparation of Intermediates

Alternative synthesis of(R)-3-amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol(Example 1 intermediate g):

a) 1-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-ethanone

To a solution of diisopropylamine (11.33 g, 112 mmol) in THF (200 ml)was added n-BuLi (44.8 ml, 2.5 mol/L in hexanes) below −50° C. Asolution of 2-bromo-5-fluoro-4-triethylsilanyl-pyridine (25 g, 86 mmol)in THF (25 ml) was added to the LDA-solution at −78° C. in a drop wisemanner below −65° C. After 70 minutes at −78° C. DMA (10.49 ml, 112mmol) was added drop wise in a fast manner to the deep red solutionkeeping the temperature below −57° C. After 30 minutes the cooling bathwas removed and the reaction mixture was allowed to reach −40° C. Thecold reaction mixture was poured on a mixture of 2M aq. HCl (160ml)/water (200 ml)/brine (100 ml). Tert.-butyl methyl ether was addedand the layers were separated. The organic phase was washed twice withbrine, dried over magnesium sulfate, filtered and evaporated to give ayellow oil. The crude product (28.67 g) was used in the next stepwithout purification.

TLC (cyclohexane/ethyl acetate 10:1): R_(f)=0.61;

LC-MS: Rt_(H1)=1.46 min; (98% purity; ESI+−MS: m/z 332 [(M+H)⁺,1Br];334);

¹H-NMR (400 MHz, CDCl₃): 7.59 (d, J=2.8 Hz, 1H), 2.70 (s, 3H), 1.06-0.83(m, 15H).

b)(R)-3-(6-Bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester

a) A mixture of titantetraethoxide (25.07 g, 110 mmol),(R)-tert.-butylsulfinamide (13.32 g, 110 mmol) and1-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-ethanone (28.67 g,85 mmol, 98% pure) in THF (250 ml) was heated under a nitrogenatmosphere for 24 hours at 60° C. The cold reaction mixture was thenconcentrated to remove ethanol. Dry toluene (2×150 ml) was added andremoved in vacuo to minimize the content of ethanol. Finally dry THF(250 ml) was added.

b) The Reformatsky reagent was prepared in a separate flask: To asuspension of zinc (17.15 g, 262 mmol) and copper(I) chloride (1.256 g,12.68 mmol) in dry THF (20 ml) were added 3 drops oftrimethylchlorosilane under nitrogen to activate the zinc. After 10minutes ethyl 2-bromo-2,2-difluoroacetate (51.5 g, 254 mmol) was addedslowly by syringe between 25 and 35° C. (Slightly exothermic withinduction period) The reaction mixture was kept in an ultrasound bathfor 45 minutes.

The sulfoximine solution was cooled to 0° C. and the Reformatsky reagentb) was quickly added to the sulfoximine solution a). The cooling bathwas removed and stirring was continued at 50° C. for 4 h.

The cold reaction mixture was poured onto ice cold aqueous 5% sulfuricacid solution (300 ml) with gentle stirring. The suspension was dilutedwith water (150 ml) and TBME (500 to 1000 ml) and was stirred at rt for30 min (pH about 3-4). The organic phase was washed thoroughly withplenty of water with backextraction of the aqueous phase. The organicphase was finally washed with brine, dried over magnesium sulfate,filtered and concentrated. The crude product (52.4 g brown-red oil,65.3% yield) was used in the next step without purification.

TLC (cyclohexane/ethyl acetate 2:1): R_(f)=0.46;

LC-MS: Rt_(H1)=1.53 min; (47% purity; ESI+−MS: m/z 559 [(M+H)⁺,1Br];561); main isomer;

LC-MS: Rt_(H1)=1.55 min; (11.9% purity; ESI+−MS: m/z 559 [(M+H)⁺,1Br];561); minor isomer.

c)(R)-3-(6-Bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester

Freshly ground KF (9.78 g, 168 mmol) was added to a solution of(R)-3-(6-bromo-3-fluoro-4-triethylsilanyl-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester (52.34 g, 56.1 mmol, 60% pure) and acetic acid (9.64ml, 168 mmol) in THF (200 ml). DMF (200 ml) was added and the suspensionwas stirred at rt. After 3 hours the reaction mixture was diluted withTBME and washed thoroughly with water, sat. sodium bicarbonate solution,water and brine, dried over magnesium sulfate, filtered and evaporated.The crude product (35.9 g yellowish-brown oil, 86% yield, 60% purity)was used in the next step without purification.

TLC (cyclohexane/ethyl acetate 2:1): R_(f)=0.30;

LC-MS: Rt_(H1)=1.10 min; (53% purity; ESI+−MS: m/z 445 [(M+H)⁺,1Br];447); main isomer;

LC-MS: Rt_(H1)=1.15 min; (7% purity; ESI+−MS: m/z 445 [(M+H)⁺,1Br];447); minor isomer.

d) (R)-2-Methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1-methyl-propyl]amide

To a solution of(R)-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-3-((R)-2-methyl-propane-2-sulfinylamino)-butyricacid ethyl ester (35.9 g, 48.4 mmol) in THF (225 ml) was portion wiseadded lithiumborohydride (2.63 g, 121 mmol) with external cooling. Theexothermic reaction was stirred ar rt for 60 min. Crushed ice and waterwas added carefully and the reaction mixture was diluted with TBME andneutralised with 2N HCl solution. The organic phase was washed withwater and brine, dried over magnesium sulfate in the presence ofcharcoal, filtered and evaporated. The crude product (29.74 gbrown-yellow sticky oil-resin) was used in the next step withoutpurification.

TLC (cyclohexane/ethyl acetate 1:1): R_(f)=0.30;

LC-MS: Rt_(H1)=0.94 min; (83% purity; ESI+−MS: m/z 403 [(M+H)⁺,1Br];405); main isomer;

LC-MS: Rt_(H1)=1.15 min; (14% purity; ESI+−MS: m/z 403 [(M+H)⁺,1Br];405); minor isomer.

e) (R)-3-Amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-olcamphersulfonic acid salt

To a cold solution of (R)-2-methyl-propane-2-sulfinic acid[(R)-1-(6-bromo-3-fluoro-pyridin-2-yl)-2,2,difluoro-3-hydroxy-1-methyl-propyl]amide(29.74 g, 61.2 mmol, 83% pure) in methanol (150 ml) was addedHCl/dioxane 4N (59.8 ml, 239 mmol). The reaction mixture was stirred for2.5 hours at rt. The solvent was evaporated and to the residue was addedTBME (300 ml) and crushed ice. The organic phase was extracted withwater (3×200 ml, pH readjusted to about 2 with each extraction using 2NHCl solution). The aq. phase was washed with TBME and solid potassiumcarbonate was added. The free base was extracted with TBME and driedover magnesium sulfate, filtered and evaporated. 15.5 g brown oil. LC-MScrude Rt=0.43 min. (85%, ES+ m/z 299, 301).

(+)-Campher sulfonic acid salt:(R)-3-Amino-3-(6-bromo-3-fluoro-pyridin-2-yl)-2,2-difluoro-butan-1-ol(13 g crude material, 36.52 mmol) and (+)-CSA monohydrate (9.13 g, 36.52mmol) in acetone (230 ml) was heated until dissolution. The solution wascooled down to rt and kept 10 hrs at −20° C. The solid was filtered andwashed with ice cold acetone and dried at 70° C. for 2 hrs in a vacuumoven. 13.66 g white solid. (theoretical yield: 19.38 g: 70%). LC-MS:Rt=0.45 min. (>98% purity, ES+m/z 299, 301 weak signal). Chiral HPLC:Chiracel OD-H, 250×4.6 mm; heptane-ethanol-methanol 95:3:2, 1 ml/min.,Rt=14.188 min 90.76%; Rt=16.17 min. 9.2%: e.e. 82%.

Recrystallization:

13.66 g was recrystallised from a mixture of hot acetone (220 ml) andethanol (50 ml). Clear solution. The flask was kept at −20° C. over theweekend. The solid was filtered, washed with ice cold acetone and driedin a vacuum oven at 70° C. White solid: 9.31 g. LC-MS Rt=0.45 min. (100%pure, ES+m/z 299, 301). Chiral HPLC: Chiracel OD-H, 250×4.6 mm;heptane-ethanol-methanol 95:3:2, 1 ml/min., Rt=14.205 min 98.21%;Rt=16.207 min. 1.7%: e.e. 96.4%. Free base: ¹H-NMR (400 MHz, DMSO-d₆): δ7.76-7.70 (m, 2H), 5.29 (br. s, 1H, OH), 3.89-3.70 (dt, 2H, CH2), 1.59(s, 3H).

Preparation of Substituted Acid Building Block Intermediates

The substituted acid building blocks were either commercially availableor can be prepared as described hereafter or in an analogous manner.

Acid-1: 3-Amino-5-(2,2,2-trifluoro-ethoxy)-pyrazine-2-carboxylic acid a)3-Amino-5-(2,2,2-trifluoro-ethoxy)-pyrazine-2-carboxylic acid methylester

A mixture of 2,2,2-trifluoro-ethanol (6.9 ml, 96 mmol) and cesiumcarbonate (1.56 g, 4.8 mmol) was stirred for 20 min,3-amino-5-chloro-pyrazine-2-carboxylic acid methyl ester [28643-16-5](600 mg, 3.2 mmol) was added and the mixture was stirred at rt for 42 h.To complete the reaction the mixture was heated to reflux for another 3h. Saturated aq. NH₄Cl was added and the mixture was extracted withEtOAc, the combined organic layers were washed with saturated aq. sodiumchloride, dried with Na₂SO₄ and evaporated. The residue was purified bychromatography on silica gel (cyclohexane to cyclohexane/EtOAc 3:7) toprovide the title compound as colorless solid.

HPLC: Rt_(H1)=0.83 min; ESIMS [M+H]⁺=252.2; ¹H-NMR (400 MHz, DMSO-d₆): δ7.66 (s, 1H), 7.60 (br. s, 2H), 5.03 (q, 2H), 3.81 (s, 3H).

b) 3-Amino-5-(2,2,2-trifluoro-ethoxy)-pyrazine-2-carboxylic acid

To a solution of3-amino-5-(2,2,2-trifluoro-ethoxy)-pyrazine-2-carboxylic acid methylester (400 mg, 1.59 mmol) in THF (20 ml) was added 1N sodium hydroxide(2.5 ml, 2.5 mmol) and the mixture was stirred at room temperature overnight. To the mixture were added 1N HCl (2.39 ml, 2.39 mmol) afterstirring for 5 min toluene was added and the solvents were evaporated toprovide the title compound together with sodium chloride as an off-whitesolid. The mixture was used for coupling reactions without furtherpurification.

HPLC: Rt_(H1)=0.71 min; ESIMS [M+H]⁺=238.2; ¹H-NMR (400 MHz, DMSO-d₆): δ7.46 (s, 1H), 4.97 (q, 2H).

Acid-2: 3-Amino-5-(2,2-difluoro-ethoxy)-pyrazine-2-carboxylic acid

The title compound was prepared by an analogous procedure to Acid-1using 2,2-difluoro-ethanol instead of 2,2,2-trifluoro-ethanol [Acid-1step a)].

HPLC: Rt_(H2)=0.60 min; ESIMS [M+H]⁺=220.2; ¹H-NMR (400 MHz, DMSO-d₆): δ12.51 (br. s, 1H), 7.62 (s, 1H), 6.43 (tt, 1H), 4.59 (td, 2H).

Acid-3: 3-Amino-5-(3-fluoro-propoxy)-pyrazine-2-carboxylic acid

The title compound was prepared by an analogous procedure to Acid-1using 3-fluoro-propan-1-ol instead of 2,2,2-trifluoro-ethanol [Acid-1step a)] and lithium hydroxide instead of sodium hydroxide [Acid-1 stepb)].

HPLC: Rt_(H1)=0.60 min; ESIMS [M+H]⁺=216.1; ¹H-NMR (400 MHz, DMSO-d₆): δ8.98 (br. s, 1H), 7.19 (s, 1H), 6.82 (br. s, 1H), 4.65 (t, 1H), 4.53 (t,1H), 4.32 (t, 2H), 2.20-1.99 (m, 2H).

Acid-4: 3-Amino-5-(3-fluoro-propoxy)-pyrazine-2-carboxylic acid

The title compound was prepared by an analogous procedure to Acid-1using 2-methoxy-ethanol instead of 2,2,2-trifluoro-ethanol [Acid-1 stepa)].

HPLC: Rt_(H1)=0.53 min; ESIMS [M+H]⁺=214.2; ¹H-NMR (400 MHz, DMSO-d₆): δ12.49 (br. s, 1H), 7.54 (br. s, 2H), 7.51 (s, 1H), 4.49-4.33 (m, 2H),3.71-3.60 (m, 2H), 3.30 (s, 3H).

Acid-5: 3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid a)3-Amino-4-oxy-pyrazine-2-carboxylic acid methyl ester

To a solution of 3-amino-pyrazine-2-carboxylic acid methyl ester[16298-03-6] (15 g, 98 mmol) in CHCl₃ (245 ml) was added mCPBA (26.6 g,108 mmol) and the resulting mixture was heated up to reflux for 40 min.To complete the reaction, more mCPBA (2.5 g) was added and the reactionwas heated to reflux for another 40 min. The mixture was diluted inDCM/Chlorofom (1/1) and then saturated aq. NaHCO₃ was added. The organiclayer was separated and the aqueous layer was extracted several timeswith DCM/Chloroform (1/1). The combined organic layers were dried withNa₂SO₄, filtered and evaporated to give a yellow solid. (12.6 g, 68%yield, 90% purity)

HPLC: Rt_(H1)=0.33 min; ESIMS [M+H]⁺=170.1; ¹H-NMR (400 MHz, DMSO-d₆): δ8.48 (d, 1H), 7.88 (d, 1H), 7.70 (br. s, 2H), 3.89 (s, 3H).

b) 3-Acetylamino-5-oxo-4,5-dihydro-pyrazine-2-carboxylic acid methylester

A solution of 3-amino-4-oxy-pyrazine-2-carboxylic acid methyl ester(11.3 g, 66.8 mmol) in Ac₂O (150 ml, 1590 mmol) and AcOH (200 ml) washeated to 120° C. for 2 h, then the reaction was cooled to rt, thesolvent was evaporated and co-evaporated with toluene. The resultingcrude material was directly used in the next step without furtherpurification.

HPLC: Rt_(H1)=0.45 min; ESIMS [M+H]⁺=212.1; ¹H-NMR (400 MHz, DMSO-d₆): δ12.55 (br. s, 1H), 11.04-10.75 (m, 1H), 7.76 (br. s, 1H), 3.81 (s, 3H),2.25 (s, 3H).

c) 3-Acetylamino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid methylester

To a solution of 3-acetylamino-5-oxo-4,5-dihydro-pyrazine-2-carboxylicacid methyl ester (300 mg, 1.136 mmol, 80% purity) in dry THF (8 ml)under argon were added triphenylphoshine (119 mg, 0.455 mmol) anddiethyl azodicarboxylate (DEAD, 0.072 ml, 0.455 mmol) at −10° C. Thereaction was stirred at −10° C. for 15 min and then 2-fluoro-ethanol(0.033 ml, 0.568 mmol) was added. The reaction was stirred at rt for 15min. To complete the reaction, more triphenylphoshine (119 mg, 0.455mmol) and DEAD (0.072 ml, 0.455 mmol) were added at −10° C. and theresulting mixture was stirred at −10° C. for 15 min before the additionof 2-fluoro-ethanol (0.033 ml, 0.568 mmol). The reaction was stirred for100 min. More triphenylphoshine (119 mg, 0.455 mmol) and DEAD (0.072 ml,0.455 mmol) were added at −10° C. and the resulting mixture was stirredat −10° C. for 15 min before the addition of 2-fluoroethanol (0.033 ml,0.568 mmol). The reaction was stirred for another 2 h. Saturated aq.NaHCO₃ was added and the mixture was extracted with EtOAc, the combinedorganic layers were washed with aq. sodium chloride, filtered and driedwith Na₂SO₄ and evaporated. The residue was purified by chromatographyon silica gel (DCM to DCM/EtOAc 9:1) to provide the title compound asyellow oil (300 mg).

HPLC: Rt_(H2)=0.63 min; ESIMS [M+H]⁺=258.4; ¹H-NMR (400 MHz, DMSO-d₆): δ10.70 (s, 1H), 8.14 (s, 1H), 4.98-4.81 (m, 1H), 4.77-4.72 (m, 1H),4.68-4.63 (m, 1H), 4.60-4.56 (m, 1H), 3.79 (s, 3H), 2.21 (s, 3H).

d) 3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid methyl ester

To a mixture of 3-acetylamino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylicacid methyl ester (330 mg, 0.962 mmol) in dry MeOH (12 ml) was addedsodium methoxide (52.0 mg, 0.962 mmol) at 0° C. The resulting suspensionwas stirred at rt for 1 h. Saturated aq. NH₄CI, was added and thenmixture was extracted with EtOAc. The combined organic layers were driedwith Na₂SO₄, filtered and evaporated. The residue was purified bychromatography on silica gel (DCM to DCM/EtOAc 9:1) to provide the titlecompound as white solid (176 mg).

HPLC: Rt_(H2)=0.62 min; ESIMS [M+H]⁺=216.1; ¹H-NMR (400 MHz, DMSO-d₆): δ7.56 (s, 1H), 7.50 (br. s, 2H), 4.87-4.79 (m, 1H), 4.74-4.67 (m, 1H),4.62-4.55 (m, 1H), 4.53-4.45 (m, 1H), 3.80 (s, 3H).

e) 3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid

To a solution of 3-amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acidmethyl ester (176 mg, 0.818 mmol) in THF (6.8 ml) was added a solutionof 1M NaOH (900 μl, 0.900 mmol). The reaction was stirred at rt for 48h. A solution of 1M HCl (1096 μL, 1.096 mmol) was added, the mixture wasevaporated to dryness and then co-evaporated with toluene to give alight purple solid (212 mg). The crude material was used directly forthe coupling reactions.

HPLC: Rt_(H2)=0.50 min; ESIMS [M+H]⁺=202.1; ¹H-NMR (400 MHz, DMSO-d₆): δ12.52 (br. s, 1H), 7.56 (br. s, 2H), 7.54 (s, 1H), 4.83 (dd, 1H), 4.71(dd, 1H), 4.60-4.54 (m, 1H), 4.50 (dd, 1H).

Acid-6: 3-Amino-5-(2-chloro-ethoxy)-pyrazine-2-carboxylic acid

The title compound was prepared by an analogous procedure to Acid-5using 2-chloro-ethanol instead of 2-fluoro-ethanol [Acid-5 step c)],adding more 1M NaOH (200 μl, 0.200 mmol) after 48 h of stirring in stepe).

HPLC: Rt_(H2)=0.62 min; ESIMS [M+H]⁺=218.1; ¹H-NMR (400 MHz, DMSO-d₆): δ12.45 (br. s, 1H), 7.69 (br s, 2H), 7.48 (s, 1H), 4.59-4.46 (m, 2H),4.01-3.93 (m, 2H).

Acid-7: 3-Amino-5-penta-deutero-ethoxy-pyrazine-2-carboxylic acid

The title compound was prepared by an analogous procedure to Acid-5using penta-deutero-ethanol instead of 2-fluoro-ethanol [Acid-5 stepc)], applying a reaction time of 24 h after the second addition oftriphenylphosphine, DEAD and penta-deutero-ethanol instead of 1 h instep c).

HPLC: Rt_(H2)=0.58 min; ESIMS [M+H]⁺=189.1 ¹H-NMR (400 MHz, DMSO-d₆): δ12.43 (br. s, 1H), 7.52 (br. s, 2H), 7.46 (s, 1H).

Acid-8:3-Amino-5-[2-(tert-butoxycarbonyl-methyl-amino)-ethoxy]-pyrazine-2-carboxylicacid

The title compound was prepared by an analogous procedure to Acid-5using tert-butyl 2-hydroxyethyl-methyl-carbamate [57561-39-4] instead of2-fluoro-ethanol [Acid-5 step c)], applying a reaction time of 24 hafter the third addition of triphenylphosphine, DEAD and2-hydroxyethyl-methyl-carbamate instead of 2 h in step c). In step e) asecond and a third addition of 1M NaOH (106 μl, 0.106 mmol) after 72 hand after 144 h were done, involving the quenching of 1M HCl (539 μl,0.539 mmol).

HPLC: Rt_(H2)=0.82 min; ESIMS [M+H]⁺=313.1 ¹H-NMR (400 MHz, DMSO-d₆,main rotamer): δ 7.32 (br. s, 1H), 4.34 (br. s, 2H), 3.55 (br. s, 2H),2.83 (s, 3H), 1.29 (br. s, 9H).

Acid-9:3-(di-tert-Butoxycarbonyl-amino)-5-difluoromethyl-pyrazine-2-carboxylicacid a) 3-Amino-5-vinyl-pyrazine-2-carboxylic acid methyl ester

To a mixture of 3-amino-5-chloro-pyrazine-2-carboxylic acid methyl ester(GB 1248146, 161 mg 0.86 mmol), tributyl(vinyl)tin (0.352 ml, 1.204mmol) and lithium chloride (102 mg, 2.498 mmol) in DMF (4 ml) was addedPdCl₂(PPh₃)₂ (30.2 mg, 0.043 mmol) and the mixture was heated to 85° C.for 2.5 h. After cooling to room temperature water was added and themixture was extracted with EtOAc, the combined organic layers werewashed with water and half saturated aq. NaCl, dried with Na₂SO₄ andevaporated. The residue was purified by chromatography on silica gel(cyclohexane to cyclohexane/EtOAc 1:9) to provide the title compound asyellow solid.

HPLC: Rt_(H4)=0.71 min; ESIMS [M+H]⁺=179.9; ¹H-NMR (600 MHz, DMSO-d₆): δ8.04 (s, 1H), 7.35 (br. s, 1H), 6.75 (dd, 1H), 6.38 (d, 1H), 5.70 (d,1H), 3.84 (s, 3H).

b) 3-(di-tert-Butoxycarbonyl-amino)-5-vinyl-pyrazine-2-carboxylic acidmethyl ester

To an ice cooled solution of 3-amino-5-vinyl-pyrazine-2-carboxylic acidmethyl ester (1.28 g, 7.14 mmol) in DCM (45 ml) was added Boc₂O (8.58 g,39.3 mmol) and the mixture was stirred at room temperature for 30 min,then the mixture was heated to 40° C. for 4 h. After cooling to roomtemperature water was added and the mixture was extracted with DCM. Thecombined organic layers were washed with 0.5N HCl and saturated aq.NaCl, dried with Na₂SO₄ and evaporated. The residue was purified bychromatography on silica gel (cyclohexane+5% NEt₃ to EtOAc+5% NEt₃) toprovide the title compound as yellow solid.

HPLC: Rt_(H1)=1.15 min; ESIMS [M-Boc]⁺=280.3; ¹H-NMR (400 MHz, DMSO-d₆):δ 8.93 (s, 1H), 7.00 (dd, 1H), 6.51 (dd, 1H), 5.86 (dd, 1H), 3.88 (s,3H), 1.34 (s, 18H).

c) 3-(di-tert-Butoxycarbonyl-amino)-5-formyl-pyrazine-2-carboxylic acidmethyl ester

A mixture of3-(di-tert-butoxycarbonyl-amino)-5-vinyl-pyrazine-2-carboxylic acidmethyl ester (1 g, 2.64 mmol) and sodium bicarbonate (0.332 g, 3.95mmol) in DCM (45 ml) and MeOH (15 ml) was cooled to −78° C. and purgedwith oxygen for 5 min. The reaction mixture was treated with ozone for40 min until the mixture turned blue. The reaction mixture was purgedwith oxygen for 10 min and with nitrogen for 10 min, then dimethylsulfide (0.487 ml, 6.59 mmol) was added at −78° C. and the mixture wasallowed to warm to room temperature. The mixture was diluted with DCMand washed with 10% aq. sodium thiosulfate. The aq. layer was extractedwith DCM and the combined organic layers were dried with Na₂SO₄ andevaporated to provide the title compound as yellow oil. The compound wasused for the next step without further purification.

¹H-NMR (400 MHz, DMSO-d₆): δ 10.07 (s, 1H), 9.24 (s, 1H), 3.94 (s, 3H),1.36 (s, 18H).

d)3-(di-tert-Butoxycarbonyl-amino)-5-difluoromethyl-pyrazine-2-carboxylicacid methyl ester

To an ice cooled solution of3-(di-tert-butoxycarbonyl-amino)-5-formyl-pyrazine-2-carboxylic acidmethyl ester (550 mg, 1.44 mmol) in DCM (20 ml) was added dropwisewithin 1 h Deoxofluor (50% in THF, 0.798 ml, 4.33 mmol). Stirring wascontinued at 0° C. for 2.5 h then the reaction mixture was allowed toroom temperature over night. Saturated aq. sodium bicarbonate was addedand the mixture extracted with EtOAc, the combined organic layers werewashed with sat. aq. sodium chloride, dried with Na₂SO₄ and evaporated.The residue was purified by chromatography on silica gel (cyclohexane+5%NEt₃ to cyclohexane+5% NEt₃/EtOAc+5% NEt₃ 1:1) to provide the titlecompound as colorless solid.

HPLC: Rt_(H1)=1.14 min; ESIMS [2M+Na]⁺=829.6; ¹H-NMR (600 MHz, DMSO-d₆):δ 9.14 (s, 1H), 7.26 (t, 1H, CHF2), 3.92 (s, 3H), 1.33 (s, 18H).

e)3-(di-tert-Butoxycarbonyl-amino)-5-difluoromethyl-pyrazine-2-carboxylicacid

To a solution of3-(di-tert-butoxycarbonyl-amino)-5-difluoromethyl-pyrazine-2-carboxylicacid methyl ester (75 mg, 0.186 mmol) in THF (2 ml) was added dropwise1N NaOH (0.205 ml, 0.205 mmol) and the reaction mixture was stirred for1.5 h. To the mixture was added 1N HCl (0.186 ml, 0.186 mmol) afterstirring for 5 min toluene was added and the solvents were evaporated toprovide the title compound together with sodium chloride as colorlesssolid. The mixture was used for coupling reactions without furtherpurification.

HPLC: Rt_(H4)=0.89 min; ESIMS [M-Boc]⁺=290.0; ¹H-NMR (400 MHz, DMSO-d₆):δ 14.30 (br. s, 1H), 9.10 (s, 1H), 7.25 (t, 1H, CHF2), 1.33 (s, 18H).

Acid-10: 3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid a)3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid methylester

To a solution of 3-methoxy-propyne (421 mg, 6 mmol),bis(triphenylphosphine)palladium(II) chloride (84 mg, 0.12 mmol),copper(I) iodide (23 mg, 0.12 mmol) and NEt₃ (1.17 ml, 8.4 mmol) in THF(10 ml) under Argon was added 3-amino-5-bromo-pyridine-2-carboxylic acidmethyl ester (277 mg, 1.2 mmol) and the mixture was heated to 80° C. for5 h. At 0° C. water (12 ml) was added and the mixture was extracted withEtOAc, the combined organic layers were washed with half-saturated aq.sodium chloride, dried with Na₂SO₄ and evaporated. The residue waspurified by chromatography on silica gel (cyclohexane tocyclohexane/EtOAc 1:4) to provide the title compound as orange solid.

HPLC: Rt_(H1)=0.67 min; ESIMS [M+H]⁺=221.1; ¹H-NMR (600 MHz, DMSO-d₆): δ7.85 (d, 1H), 7.33-7.22 (m, 1H), 6.77 (s, 2H), 4.35 (s, 2H), 3.80 (s,3H), 3.33 (s, 3H).

b) 3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid

To a solution of 3-amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylicacid methyl ester (263 mg, 1.2 mmol) in THF (6 ml) was added 1N lithiumhydroxide (1.32 ml, 1.32 mmol) at 0° C. and the mixture was stirred atroom temperature for 2 h. To the mixture was added 1N HCl (1.2 ml, 1.2mmol) at 0° C., after stirring for 5 min toluene was added and thesolvents were evaporated to provide the title compound together withlithium chloride as an off-white solid. The mixture was used forcoupling reactions without further purification.

HPLC: Rt_(H1)=0.45 min; ESIMS [M+H]⁺=207.2; ¹H-NMR (600 MHz, DMSO-d₆): δ7.84 (s, 1H), 7.30 (s, 1H), 6.92 (br. s., 1H), 4.35 (s, 2H), 3.33 (s,3H).

Acid-11:3-Chloro-5-[3-(tetrahydro-pyran-2-yloxy)-prop-1-ynyl)-pyridine-2-carboxylicacid

The title compound was prepared by an analogous procedure to Acid-xxusing 5-bromo-3-chloro-pyridine-2-carboxylic acid methyl ester insteadof 3-amino-5-bromo-pyridine-2-carboxylic acid methyl ester and2-prop-2-ynyloxy-tetrahydro-pyran instead of 3-methoxy-propyne [Acid-xxstep a)].

HPLC: Rt_(H2)=0.68 min; ESIMS [M+H]⁺=296.1; ¹H-NMR (400 MHz, DMSO-d₆): δ14.02 (br. s, 1H), 8.65 (s, 1H), 8.26 (s, 1H), 4.84 (br. s, 1H),4.66-4.36 (m, 2H), 3.85-3.64 (m, 1H), 3.58-3.41 (m, 1H), 1.80-1.61 (m,2H), 1.60-1.41 (m, 4H)

Acid-12: 3-Chloro-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid

To a solution of 3-methoxy-propyne (421 mg, 6 mmol),bis(triphenylphosphine)palladium(II) chloride (84 mg, 0.12 mmol),copper(I) iodide (23 mg, 0.12 mmol) and NEt₃ (1.17 ml, 8.4 mmol) in THF(10 ml) under Argon was added 3-chloro-5-bromo-pyridine-2-carboxylicacid methyl ester (284 mg, 1.2 mmol) and the mixture was heated to 80°C. for 5 h. At 0° C. water (12 ml) was added and the mixture wasextracted with EtOAc. The aq. Phase was acidified to pH 1 by addition of1N HCl, extracted with DCM. The combined DCM extracts were washed withhalf-saturated aq. sodium chloride, dried with Na₂SO₄ and evaporated toprovide the title compound as an off-white solid, which was used forcoupling reactions without further purification.

HPLC: Rt_(H1)=0.49 min; ESIMS [M+H]⁺=226.3; ¹H-NMR (600 MHz, DMSO-d₆): δ14.02 (br. s., 1H), 8.64 (s, 1H), 8.24 (s, 1H), 4.39 (s, 2H), 3.33 (s,3H).

Acid-13: 3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid a)3-Amino-543-(tert-butyl-dimethyl-silanyloxy)-prop-1-ynyl)-pyridine-2-carboxylicacid methyl ester

The title compound was prepared by an analogous procedure to Acid-10using tert-butyl-dimethyl-prop-2-ynyloxy-silane instead of3-methoxy-propyne [Acid-10 step a)].

HPLC: Rt_(H1)=1.23 min; ESIMS [M+H]⁺=321.2; ¹H-NMR (600 MHz, DMSO-d₆): δ7.81 (s, 1H), 7.26 (d, 1H), 6.78 (br. s, 2H), 4.57 (s, 2H), 3.79 (s,3H), 0.89 (s, 9H), 0.12 (s, 6H).

b) 3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid methylester

To a solution of3-amino-543-(tert-butyl-dimethyl-silanyloxy)-prop-1-ynyl)-pyridine-2-carboxylicacid methyl ester (711 mg, 2.22 mmol) in DCM (6 ml) was added 10.2 mlTFA (133 mmol) at 0° C. and the mixture was stirred at room temperaturefor 17 h. To the mixture was added toluene (18 ml) and the solvents wereevaporated. The residue was dissolved in EtOAc (66 ml) and washed withaq. 1M Na₂CO₃ solution, the aq. Phase was extracted back with EtOAc. Thecombined organic layers were washed with half-saturated aq. sodiumchloride, dried with Na₂SO₄ and evaporated. The residue was purified bychromatography on silica gel (DCM to DCM/MeOH 94:6) to provide the titlecompound as an off-white solid.

HPLC: Rt_(H1)=0.50 min; ESIMS [M+H]⁺=207.1; ¹H-NMR (600 MHz, DMSO-d₆): δ7.82 (s, 1H), 7.24 (s, 1H), 6.77 (br s, 2H), 5.43 (br. s, 1H), 4.32 (s,2H).

c) 3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid

To a solution of 3-amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylicacid methyl ester (297 mg, 1.44 mmol) in THF (10 ml) was added 1Nlithium hydroxide and the mixture was vigorously stirred at roomtemperature for 4.5 h. To the mixture was added 4N HCl (0.47 ml, 1.87mmol), after dilution with toluene the solvent was evaporated, theresidue was suspended in toluene and evaporated (twice). The residue wassuspended in TBME/hexane, filtered and the solid dried under reducedpressure at 50° C. to provide the title compound together with lithiumchloride as a brown solid. The mixture was used for coupling reactionswithout further purification.

HPLC: Rt_(H5)=1.93 min; ESIMS [M+H]⁺=193.0; ¹H-NMR (600 MHz, DMSO-d₆): δ7.83 (s, 1H), 7.28 (s, 1H), 6.94 (br. s, 1H), 4.33 (s, 2H).

Acid-14: 3-Amino-5-difluoromethyl-pyridine-2-carboxylic acid a)5-Difluoromethyl-3-nitro-pyridine-2-carboxylic acid tert-butyl ester

The title compound was prepared by an analogous reaction sequence toAcid-9 using 5-bromo-3-nitro-pyridine-2-carboxylic acid instead of3-amino-5-chloro-pyrazine-2-carboxylic acid methyl ester in step a) andomitting step b).

HPLC: Rt_(H1)=1.07 min; ESIMS [M+H]⁺=275.3; ¹H-NMR (600 MHz, DMSO-d₆): δ9.18 (s, 1H), 8.82 (s, 1H), 7.31 (t, 1H, CHF2), 1.55 (s, 9H).

b) 5-Difluoromethyl-3-nitro-pyridine-2-carboxylic acid

In a mixture of 5 ml DCM and 2.5 ml TFA was dissolved 345 mg (1.26 mmol)5-difluoromethyl-3-nitro-pyridine-2-carboxylic acid tert-butyl ester andthe reaction mixture was stirred for 4 h. Toluene was added and thesolvents were evaporated to provide the title compound as colorlesssolid.

HPLC: Rt_(H1)=0.31 min; ESIMS [2M−H]⁻=435.3; ¹H-NMR (600 MHz, DMSO-d₆):δ 14.59 (br. s, 1H), 9.16 (s, 1H), 8.80 (s, 1H), 7.31 (t, 1H, CHF2).

c) 3-Amino-5-difluoromethyl-pyridine-2-carboxylic acid

To a solution of 265 mg (1.22 mmol)5-difluoromethyl-3-nitro-pyridine-2-carboxylic acid in EtOH was added 50mg Raney-Nickel (Degussa B113W) and the reaction mixture was keptshaking under a hydrogen atmosphere for 16 h. The catalyst was filteredoff (Celite) and washed with EtOH and the filtrate was evaporated toprovide the title compound as off-white solid.

HPLC: Rt_(H1)=0.34 min; ESIMS [M+H]⁺=189.2; ¹H-NMR (600 MHz, DMSO-d₆): δ7.98 (s, 1H), 7.39 (s, 1H), 7.09 (t, 1H, CHF2), 7.02 (br. s, 2H).

Acid-15: 3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid a)3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carbonitrile

To a solution of 3-chloro-5-hydroxy-pyridine-2-carbonitrile[1262860-70-7] (0.200 g, 1.23 mmol) in THF (15 ml) was added at 0° C.2,2-difluoro-ethanol (0.123 g, 1.48 mmol) and triphenylphosphine (0.484g, 1.84 mmol). After stirring for 10 min at 0° C. DIAD (0.373 g, 1.84mmol) was added and the reaction mixture was stirred for 2 h at 0° C.followed by 16 h at 25° C. The reaction mixture was concentrated and thetitle compound was obtained after CombiFlash chromatography on silicagel (hexane/EtOAc 20:1 to 1:1) as a colorless oil.

TLC (hexane-EtOAc 1:1): Rf=0.61; UPLC Rt_(H6)=0.965 min; ESIMS: 217[(M−H)⁻]; ¹H-NMR (400 MHz, CDCl₃): δ 8.31 (d, 1H), 7.32 (d, 1H), 6.12(tt, 1H), 4.31 (dt, 2H).

b) 3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid

To a solution of3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carbonitrile (0.202 g, 0.878mmol) in dioxane (4 ml) was added 4N NaOH (2.2 ml, 8.8 mmol) and theresulting reaction mixture was stirred for 28 h at 85° C. The reactionmixture was diluted with water and extracted with EtOAc. The aqueousphase was acidified with 4N HCl and evaporated to dryness. The titlecompound was extracted with DCM/MeOH (9/1), pushed through a plug ofCelite and was obtained after evaporation as a light yellow solid.

UPLC Rt_(H6)=0.655 min; ESIMS: 236 [(M−H)⁻]; ¹H-NMR (400 MHz, CD₃OD): δ8.31 (d, 1H), 7.68 (d, 1H), 6.23 (tt, 1H), 4.44 (dt, 2H); ¹⁹F-NMR (400MHz, CD₃OD) 128.0 (dt, 2F).

Acid-16: 3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid a)2,3-Dichloro-5-fluoromethoxy-pyridine

To a solution of 5,6-dichloro-pyridin-3-ol [11860-92-9] (500 mg, 3.05mmol) and K₂CO₃ (632 mg, 4.57 mmol) in dry ACN (12 ml) was addedfluoro-iodomethane (1.156 ml, 9.15 mmol) at 0° C. The light yellowsuspension was stirred for 5 min at 0° C. and then heated up to 120° C.for 30 min. Saturated aq. NH₄Cl was added, followed by EtOAc. Theorganic layer was separated and the aqueous layer was extracted twicewith EtOAc. The combined organic layers were washed with brine, driedwith Na₂SO₄, filtered and evaporated to give a brown oil. The crudematerial was directly used in the next step without furtherpurification.

HPLC: Rt_(H2)=0.95 min; ESIMS [M+H]⁺=198.1; ¹H-NMR (400 MHz, DMSO-d₆): δ8.31 (dd, 1H), 8.07 (d, 1H), 6.05 (s, 1H), 5.91 (s, 1H).

b) 3-Chloro-5-fluoromethoxy-pyridine-2-carbonitrile

To a solution of 2,3-dichloro-5-fluoromethoxy-pyridine (1.18 g, 6.02mmol) in dry DMF (14.00 ml) were added Zinc cyanide (0.341 g, 2.90 mmol)and Zinc powder (3.94 mg, 0.060 mmol). The suspension was flushed withArgon (3×). Then tetrakis(triphenylphosphine)palladium(0) (0.570 g,0.494 mmol) was added. The reaction was heated to 145° C. for 2 h. Waterwas added and the aqueous layer was extracted twice with Et₂O. Thecombined organic layers were washed with brine, dried with Na₂SO₄,filtered and evaporated. The residue was purified by chromatography onsilica gel (cyclohexane to cyclohexane/EtOAc 7:3) to provide the titlecompound as yellow oil (515 mg).

HPLC: Rt_(H2)=0.81 min; ESIMS [M+H]⁺=187.0; ¹H-NMR (400 MHz, DMSO-d₆): δ8.61 (s, 1H), 8.16 (s, 1H), 6.15 (s, 1H), 6.02 (s, 1H).

c) 3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid

To a solution of 3-chloro-5-fluoromethoxy-pyridine-2-carbonitrile (80mg, 0.429 mmol) in EtOH (2.4 ml) was added 1M NaOH (1.21 ml, 1.201 mmol)and the resulting solution was stirred at 70° C. over night. To completethe reaction, more 1M NaOH (1.2 ml, 1.201 mmol) was added and thereaction was stirred at 70° C. for 8 h. More 1M NaOH (1.2 ml, 1.201mmol) was added and the reaction was stirred over night. Then 1M HCl(3.45 ml, 3.45 mmol) was added. The aqueous layer was extracted twicewith EtOAc. The combined organic layers were dried with Na₂SO₄, filteredand evaporated to give a light pink solid. Mixture of 80 mg, 35% of3-chloro-5-fluoromethoxy-pyridine-2-carboxylic acid, 38% of3-chloro-5-ethoxy-pyridine-2-carboxylic acid.

3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid

HPLC: Rt_(H2)=0.42 min; ESIMS [M+H]⁺=206.1; ¹H-NMR (400 MHz, DMSO-d₆): δ13.36 (br. s, 1H), 8.29 (d, 1H), 7.66 (d, 1H), 6.09 (s, 1H), 5.96 (s,1H).

3-Chloro-5-ethoxy-pyridine-2-carboxylic acid

HPLC: Rt_(H2)=0.59 min; ESIMS [M+H]⁺=202.1; ¹H-NMR (400 MHz, DMSO-d₆): δ13.66 (br. s, 1H), 8.45 (d, 1H), 8.29 (d, 1H), 4.21 (q, 2H), 1.36 (t,3H).

The crude mixture of acids was used for the couling reaction withoutfurther purification.

Acid-17: 3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid a)3-Amino-5-((Z)-2-ethoxy-vinyl)-pyrazine-2-carboxylic acid methyl ester

A mixture of 3-amino-5-chloro-pyrazine-2-carboxylic acid methyl ester[28643-16-5] (2 g, 10.66 mmol), lithium chloride (1.582 g, 37.3 mmol),Pd(PPh₃)₂Cl₂ (0.748 g, 1.066 mmol) andtributyl-((Z)-2-ethoxy-vinyl)-stannane (6.42 ml, 19.19 mmol) in DMF (104ml) under argon was heated at 80° C. bath temperature for 1.5 h. Asaturated. aq. NH₄Cl was added and the mixture was extracted with MTBE,then once with EtOAc/THF 3/1. The combined organic layer was washed withbrine, dried with Na₂SO₄, filtered and concentrated under reducedpressure. The residue was purified by chromatography on silica gel(cyclohexane to cyclohexane/EtOAc 1:9) to provide the title compound asyellow oil (1.96 g).

HPLC: Rt_(H2)=0.69 min; ESIMS [M+H]⁺=225.1; ¹H-NMR (400 MHz, DMSO-d₆): δ8.42 (s, 1H), 7.18 (br. s, 2H), 6.88 (d, 1H), 5.23 (d, 1H), 4.15 (q,2H), 3.82 (s, 3H), 1.32 (t, 3H).

b) 3-Amino-5-(2,2-dimethoxy-ethyl)-pyrazine-2-carboxylic acid methylester

A solution of 3-amino-5-((Z)-2-ethoxy-vinyl)-pyrazine-2-carboxylic acidmethyl ester (220 mg, 0.986 mmol) in 3M HCl in MeOH (210 μl, 6.90 mmol)was heated at 55° C. over night. A solution of 10% of NaHCO₃ was addedthe mixture was extracted with EtOAc. The combined organic layer wasdried with Na₂SO₄, filtered and concentrated under reduced pressure toobtain a brown solid (141 mg). The crude material was directly used inthe next step without further purification.

HPLC: Rt_(H1)=0.59 min; ESIMS [M+H]⁺=242.2.

c) 3-Amino-5-(2-methoxy-vinyl)-pyrazine-2-carboxylic acid methyl ester

To a solution of 3-amino-5-(2,2-dimethoxy-ethyl)-pyrazine-2-carboxylicacid methyl ester (300 mg, 1.244 mmol) and Et₃N (1.213 ml, 8.70 mmol) inDCM (10 ml) at −10° C. was added dropwise timethylsilyltrifluoromethanesulfonate (0.809 ml, 4.48 mmol). The reaction mixturewas stirred at room temperature for 100 min. A saturated solution ofNaHCO₃ was added and the mixture was extracted twice with DCM. Thecombined organic layers were washed with NH₄Cl solution and brine, driedwith Na₂SO₄, filtered and concentrated under reduced pressure to obtaina brown oil (560 mg). The resulting crude material (mixture of E and Z)was directly used in the next step without further purification.

HPLC: Rt_(H1)=0.63 min; ESIMS [M+H]⁺=210.1.

d) 3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid methyl ester

A solution of 3-amino-5-(2-methoxy-vinyl)-pyrazine-2-carboxylic acidmethyl ester (260 mg, 1.24 mmol) and Pd/C 10% (50 mg) in EtOH (10 ml)was stirred at rt and under an atmosphere of hydrogen for 17 h. Tocomplete the reaction, more Pd/C 10% (84 mg) was added and the reactionwas stirred under an atmosphere of hydrogen for 37 h. The suspension wasfiltered off and washed with EtOH and then residual solution wasevaporated. The residue was purified by chromatography on silica gel(DCM to DCM/MeOH 9:1) to provide the title compound as yellow solid (147mg).

HPLC: Rt_(H2)=0.54 min; ESIMS [M+H]⁺=212.2; ¹H-NMR (400 MHz, DMSO-d₆): δ7.84 (s, 1H), 7.31 (br. s, 2H), 3.83 (s, 3H), 3.68 (t, 2H), 3.23 (s,3H), 2.87 (t, 3H).

e) 3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid

To a solution of 3-amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acidmethyl ester (147 mg, 0.696 mmol) in THF (14 ml) was added 1M NaOH (1.74ml, 1.74 mmol) and the reaction mixture was stirred at room temperaturefor 2 h. 1M HCl (1.601 ml, 1.601 mmol) was added to the reactionmixture. The resulting mixture was evaporated and co-evaporated withtoluene. The resulting crude material was directly used in the couplingstep without further purification.

HPLC: Rt_(H2)=0.41 min; ESIMS [M+H]⁺=198.1; ¹H-NMR (400 MHz, DMSO-d₆): δ7.68 (s, 1H), 7.62 (br. s, 2H), 3.65 (t, 2H), 3.23 (s, 3H), 2.81 (t,3H).

Acid-18: 3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylicacid a) 3-Amino-6-chloro-5-(1-ethoxy-vinyl)-pyrazine-2-carboxylic acidmethyl ester

A mixture of 3-amino-5,6-dichloro-pyrazine-2-carboxylic acid methylester [1458-18-0] (600 mg, 2.62 mmol), lithium chloride (389 mg, 9.17mmol), Pd(PPh₃)₂Cl₂ (184 mg, 0.262 mmol) andtributyl-(1-ethoxy-vinyl)-stannane [97674-02-7] (1.6 ml, 4.50 mmol) inDMF (27 ml) under argon was heated at 80° C. bath temperature for 3 hand 50 min. Saturated aq. NH₄Cl was added and the mixture was extractedwith MTBE (3×). The combined organic layers were washed with brine,dried with Na₂SO₄, filtered and concentrated under reduced pressure. Theresidue was purified by chromatography on silica gel (cyclohexane tocyclohexane/EtOAc 7:3) to provide the title compound as yellow solid(433 mg).

HPLC: Rt_(H2)=0.94 min; ESIMS [M+H]⁺=258.1; ¹H-NMR (400 MHz, DMSO-d₆): δ7.59 (br. s, 2H), 4.64 (d, 1H), 4.58 (d, 1H), 3.91 (q, 3H), 3.86 (s,3H), 1.31 (t, 2H).

b) 5-Acetyl-3-amino-6-chloro-pyrazine-2-carboxylic acid methyl ester

A solution of 3-amino-6-chloro-5-(1-ethoxy-vinyl)-pyrazine-2-carboxylicacid methyl ester (46 mg, 0.190 mmol) and para-toluenesulfonic acidmonohydrate (73.8 mg, 0.388 mmol) in THF (2.85 ml) was stirred at rt for1 h. Saturated aq. NaHCO₃ was added and the mixture was extracted twicewith DCM. The combined organic layers were washed with brine, dried withNa₂SO₄, filtered and concentrated under reduced pressure to obtain ayellow solid (46 mg). This material was used for the next step withoutfurther purification.

HPLC: Rt_(H2)=0.73 min; ESIMS [M+H]⁺=230.1; ¹H-NMR (400 MHz, DMSO-d₆): δ7.70 (br. s, 2H), 3.83 (s, 3H), 2.58 (s, 3H).

c) 3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acidmethyl ester

To a cloudy yellow solution of5-acetyl-3-amino-6-chloro-pyrazine-2-carboxylic acid methyl ester (178mg, 0.775 mmol) in dry DCM (7.75 ml) was added Deoxofluor 50% in toluene(858 μl, 2.326 mmol). The reaction was stirred at rt over the weekend.More Deoxofluor 50% in toluene was added (six times 858 μL, 2.326 mmol)within 3 days to complete the reaction. Saturated aq. NaHCO₃ was addedand the mixture was extracted twice with EtOAc. The combined organiclayers were washed with aq. citric acid, dried with Na₂SO₄, filtered andconcentrated under reduced pressure. The residue was purified bychromatography on silica gel (cyclohexane to cyclohexane/EtOAc 7:3) toprovide the title compound as yellow solid (136 mg).

HPLC: Rt_(H2)=0.91 min; ESIMS [M+H]⁺=252.1; ¹H-NMR (400 MHz, DMSO-d₆): δ7.75 (br. s, 2H), 3.88 (s, 3H), 2.02 (t, 3H).

d) 3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid

To a solution of3-amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acidmethyl ester (136 mg, 0.541 mmol) in THF (5.40 ml) was added 1M LiOH(595 μl, 0.595 mmol) at 0° C. The resulting brown solution was warmed upto rt for 5 h. More 1M LiOH (95 μl, 0.095 mmol) was added at 0° C. andthe reaction was stirred at rt for 1 h. Then 1M HCl (632 μl, 0.632 mmol)was added and then the resulting mixture was evaporated to dryness. Theresulting crude material was directly used in the coupling step withoutfurther purification.

HPLC: Rt_(H2)=0.63 min; ESIMS [M+H]⁺=238.1; ¹H-NMR (400 MHz, DMSO-d₆): δ13.69 (br. s, 1H), 7.75 (br. s 2H), 2.02 (t, 3H).

Acid-19: 3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid a)3-Chloro-5-(1-ethoxy-vinyl)-pyridine-2-carboxylic acid methyl ester

To a solution of 5-bromo-3-chloro-pyridine-2-carboxylic acid methylester [1458-18-0] (376 mg, 1.5 mmol) in dioxane (3.7 ml) was addedtributyl-(1-ethoxy-vinyl)-stannane [97674-02-7] (596 mg, 1.65 mmol), thesolution was degassed and flushed with nitrogen (3×), Pd(PPh₃)₄ (87 mg,0.075 mmol) was added, after degassing and flushing with nitrogen themixture was heated to reflux for 4 h. The reaction mixture was dilutedwith EtOAc and treated with 10% aq. KF, the precipitate was filtered offand the layers were separated. The aq. Phase was extracted with EtOAc,the combined organic layers were washed with sat. aq. NaCl, dried withMgSO₄, filtered and concentrated under reduced pressure. The residue waspurified by chromatography on silica gel (cyclohexane/EtOAc 12:1 to 6/1)to provide the title compound as yellow solid.

HPLC: Rt_(H7)=2.822 min; ESIMS [M+H]⁺=242.0/244.0; ¹H-NMR (600 MHz,DMSO-d₆): δ 8.91-8.78 (m, 1H), 8.29-8.18 (m, 1H), 5.19 (d, 1H), 4.60 (d,1H), 3.93 (q, 2H), 3.92 (s, 3H), 1.37 (t, 3H).

b) 5-Acetyl-3-chloro-pyridine-2-carboxylic acid methyl ester

To a solution of 3-chloro-5-(1-ethoxy-vinyl)-pyridine-2-carboxylic acidmethyl ester (359 mg, 1.485 mmol) in THF (3.6 ml) was addedpara-toluenesulfonic acid monohydrate (565 mg, 2.97 mmol) and themixture was stirred for 1 h. The reaction mixture was diluted with TBMEand sat. aq. NaHCO₃, the layers were separated and the aq. Phase wasextracted with TBME. The combined organic layers were washed with sat.aq. NaHCO₃ and sat. aq. NaCl, dried with MgSO₄, filtered andconcentrated under reduced pressure. The residue was purified bychromatography on silica gel (cyclohexane/EtOAc 9:1 to 6/1) to providethe title compound as yellow solid.

HPLC: Rt_(H8)=2.604 min; ESIMS [M+H]⁺=214.0/216.0; ¹H-NMR (600 MHz,DMSO-d₆): δ 9.17-8.99 (m, 1H), 8.63-8.46 (m, 1H), 3.96 (s, 3H), 2.69 (s,3H).

c) 3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid methylester

To a solution of 5-acetyl-3-chloro-pyridine-2-carboxylic acid methylester (278 mg, 1.30 mmol) in DCM (2.8 ml) was added Deoxofluor® (50 w-%in toluene, 1.44 ml, 3.9 mmol) and the reaction mixture was stirredprotected from sunlight at rt for 6 h, more Deoxofluor® (50 w-% intoluene, 1.44 ml, 3.9 mmol) was added and the mixture was stirred overnight. The reaction mixture was poured on cold sat. aq. NaHCO₃ (stronggas evolution), TBME was added and the layers were separated. The aq.phase was extracted with TBME, the combined TBME layers were washed withsat. aq. NaHCO₃, sat. aq. NaCl, dried with MgSO₄, filtered andevaporated. The residue was purified by chromatography on silica gel(cyclohexane/EtOAc 95:5 to 93/7) to provide the title compound ascolorless oil.

HPLC: Rt_(H8)=3.140 min; ESIMS [M+H]⁺=236.0/238.0; ¹H-NMR (600 MHz,DMSO-d₆): δ 8.84 (s, 1H), 8.40 (s, 1H), 3.95 (s, 3H), 2.07 (t, 3H).

d) 3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid

To a solution of 3-chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylicacid methyl ester (272 mg, 1.154 mmol) in THF (6 ml) was added LiOH(30.4 mg, 1.27 mmol) in water (0.5 ml) and the mixture was stirred for3.5 h. To the mixture was added 6N HCl (0.212 ml, 1.27 mmol) and thesolvent was evaporated. The residue was taken up in toluene andevaporated (2×) to provide the title compound as colorless solidtogether with LiCl. This material was directly used in the coupling stepwithout further purification.

HPLC: Rt_(H5)=2.743 min; ESIMS [M+H]⁺=222.0/224.0; ¹H-NMR (600 MHz,DMSO-d₆): δ 8.76 (s, 1H), 8.29 (s, 1H), 3.37 (br. s, 1H), 2.06 (t, 3H).

1. A method of treating Alzheimer's Disease or mild cognitive impairmentcomprising, administering to a patient in need thereof, a compound offormula (I), or a pharmaceutically acceptable salt thereof,

wherein R¹ and R² are independently hydrogen or halogen; R³ and R⁴ areindependently hydrogen or C₁₋₃alkyl; or R³ and R⁴ taken together arecyclopropyl; or R¹ and R⁴ are hydrogen and R² and R³ taken together are—CH₂—O—CH₂—; R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl;and R⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising1, 2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl.
 2. The method according to claim 1, or apharmaceutically acceptable salt thereof, wherein R¹ and R² are bothfluoro.
 3. The method according to claim 1, or a pharmaceuticallyacceptable salt thereof, wherein R³ and R⁴ are both hydrogen.
 4. Themethod according to claim 1, or a pharmaceutically acceptable saltthereof, wherein R⁵ is methyl.
 5. The method according to claim 1, or apharmaceutically acceptable salt thereof, wherein R⁶ is a 6-memberedmonocyclic heteroaryl comprising 1, 2, 3 or 4 heteroatoms independentlyselected from N, O and S, and wherein said phenyl or heteroaryl isoptionally substituted by 1, 2, 3 or 4 substituents independentlyselected from halogen, cyano, amino, hydroxy, C₁₋₄alkyl,halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio, halogen-C₁₋₄alkoxy,C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkoxy andC₁₋₄alkoxy-C₁₋₄alkylthio.
 6. The method according to claim 1, or apharmaceutically acceptable salt thereof, wherein R⁶ is a pyridin-2-ylgroup which is substituted by 2 substituents and wherein one of thesubstituents is located at the para position and one of the substituentsis located at the ortho position of the pyridin-2-yl group relative tothe amide linker and wherein the substituents are independently selectedfrom halogen, cyano, amino, hydroxy, methyl, trifluoromethyl, methoxyand trifluoromethoxy.
 7. The method according to claim 1 which isselected from: 5-Cyano-3-methyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4,6,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;5-Cyano-3-methyl-pyridine-2-carboxylic acid{6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid{6-[(R)-2-amino-5,5-difluoro-4-(2-methoxy-ethyl)-5,6-dihydro-4H-[1,3]oxazin-4-yl]-5-fluoro-pyridin-2-yl}-amide;3-Chloro-5-trifluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-trifluoromethyl-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3,5-Dichloro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(2,2,2-trifluoro-ethoxy)pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(2,2-difluoro-ethoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(3-fluoro-propoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;5-Methoxy-3-methyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(3-methoxy-prop-1-ynyl)-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-fluoromethoxy-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;3-Amino-5-(2-methoxy-ethoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-fluoro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-chloro-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-pyridine-2-carboxylicacid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;3-Chloro-5-(3-methoxy-prop-1-ynyl)pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-difluoromethyl-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(2-chloro-ethoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-(2,2-difluoro-ethoxy)-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(2-fluoro-ethoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-fluoromethoxy-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-ethoxy-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(penta-deutero-ethoxy)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-(2-methoxy-ethyl)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;4-Chloro-1-difluoromethyl-1H-pyrazole-3-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-(3-hydroxy-prop-1-ynyl)-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Amino-5-difluoromethyl-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]amide;3-Amino-6-chloro-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;5-Cyano-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;3-Chloro-5-(1,1-difluoro-ethyl)-pyridine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;and 3-Amino-5-(1,1-difluoro-ethyl)-pyrazine-2-carboxylic acid[6-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-5-fluoro-pyridin-2-yl]-amide;and pharmaceutically acceptable salts thereof.
 8. A method of treatingAlzheimer's Disease or mild cognitive impairment comprising,administering to a patient in need thereof,

or a salt thereof.
 9. A method of treating Alzheimer's Disease or mildcognitive impairment comprising, administering to a patient in needthereof,

or a salt thereof.
 10. A combination comprising a therapeuticallyeffective amount of a compound, or a pharmaceutically acceptable saltthereof, of formula (I),

wherein R¹ and R² are independently hydrogen or halogen; R³ and R⁴ areindependently hydrogen or C₁₋₃alkyl; or R³ and R⁴ taken together arecyclopropyl; or R¹ and R⁴ are hydrogen and R² and R³ taken together are—CH₂—O—CH₂—; R⁵ is C₁₋₃alkyl, halogen-C₁₋₃alkyl or C₁₋₃alkoxy-C₁₋₃alkyl;and R⁶ is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising1, 2, 3 or 4 heteroatoms independently selected from N, O and S, andwherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3or 4 substituents independently selected from halogen, cyano, amino,hydroxy, C₁₋₄alkyl, halogen-C₁₋₄alkyl, halogen-C₁₋₄alkylthio,halogen-C₁₋₄alkoxy, C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkyl,C₁₋₄alkoxy-C₁₋₄alkoxy, C₁₋₄alkoxy-C₁₋₄alkylthio, C₁₋₄alkoxy-C₂₋₄alkenyl,C₁₋₄alkoxy-C₂₋₄alkynyl, hydroxy-C₁₋₄alkyl, hydroxy-C₂₋₄alkenyl andhydroxy-C₂₋₄alkynyl, and a second drug substance, for simultaneous orsequential administration.